They say that 40 is the new 30 – and for many aspects of life, that may well be true. Socially, the stuff we once did in our third decade is now being happily deferred to our fourth, and our fourth to our fifth. Marriage, children, staying in and being sensible – it's all happening later than ever before.

But if there's one area the maxim doesn't apply to, it's health. I'm sorry to say that 40 is still the same 40 when it comes to your body – and it leads to the same 50, 60, 70 and beyond . You can live as though you're still 28, but the chances are that you'll feel the repercussions sooner rather than later. A depressing thought, I know, but a useful one to keep in mind.

The better news is that there's no reason to feel unhealthy in your 40s – and the lifestyle tweaks that can help should also keep you good and honest as your grow older.

As a personal trainer, I invite all of my clients to split their focus 50/50: that's 50pc on the here and now, and 50pc on the future. You should be able to be 40 and fit, while also insuring yourself against things that often kick in down the line – like postural problems, mental ill-health, and major diseases.

Before we get started, a small disclaimer: this article represents a theoretical blueprint and is not intended as personal medical advice. As ever, you should consult your GP if you are troubled by a specific problem – be it mental or physical.

Right, on with the show ...

How to future proof your body

Just 30 minutes of exercise a day should help you offset osteoporosis, hold on to muscle mass, maintain your natural range of motion, avoid back pain, lower your risk of heart problems and maintain a healthy sex life.

How should you spend those minutes? By mixing up the below ...

1. Resistance training

After the age of 40, we typically lose about 1pc of muscle mass each year. This in turn slows your metabolism, weakens your structure, and lessens your athletic appearance.

Weightlifting is your friend here. I'm not talking about lifting huge chucks of cast iron, like those beefcakes on Muscle Beach – I mean low intensity, relaxed movements using manageable weights and focusing on compound movements. This will help to send your body a signal that it needs to hold onto its hard earned muscle mass – but crucially not overwork it. Try not to lift more than 80pc of your personal best, and never train to failure (ie lift until you can lift no more).

The idea here is to get all the strength benefits out of lifting weights without suffering burnout, which puts unnecessary stress on your nervous system and is much harder to recover from in your 40s.

2. Yoga / Pilates

One of the biggest mistakes many of us make throughout our 20’s and 30’s is neglecting mobility. We sit for hours on end at a desk, then hare around the five-a-side come evening without so much as a single stretch to warm up. Come 40, we're planks of wood (only not so upright).

I'm sure you've read before that yoga is the solution – but what is less well known is that it protects not just your muscles but also your spine, cartilage and tendons. Stretching regularly will make you a lot more resilient to injury as you make your way through mid-life.

As for the yoga vs Pilates questions: Pilates uses more traditional exercise protocol and is very outcome dependent, whereas yoga is a little more of a mind/body practice, where bodily benefits serve as a prelude to the ability to still one’s mind. Which should you do? It's really up to you. My verdict? Both!

3. Daily mobility drills

So you sit all day at a desk, hare around the five-a-side pitch ... and know with certainty that you won't be incorporating yoga into your daily routine?

It's ok. I get it. Yoga isn't for everyone, and no-one feels like they have half an hour to spare every day anyway. However, that doesn't mean to say you're beyond hope. A short daily mobility drill only takes five minutes and is an excellent way to start the day, allowing you to wake up the body after a night's sleep. It will also give you cash in the bank ahead of the desk sitting, helping to stall issues with poor posture, neck and lower back.

Aim to rotate your hips, shoulders, knees and ankles, and open up the spine. Simple exercises like squats, lunges, planks, cat stretches are all an excellent idea.

4. Low Intensity Cardio

Low intensity cardio is one of the biggest game changers I’ve come across in my time in the fitness industry. I've seen so many people incorporate it into their daily routine and become lean in just a few months.

What does it mean? Technically, you're aiming to train at a specific heart rate – somewhere around the 105-120 beats per minute band, which is the area where your body burns fat for energy.

In practice, you don't have to have a heart rate strap or fiddly FitBit. Just go for a brisk stroll or gentle bike ride, or try a dancing class (well, maybe not break dancing) – you'll find you operate somewhere around the desired band. Not only will these activities burn fat, but they'll also lower your cortisol levels, helping you deal with the dollop of stress you wade through every day.

5. Listen to your body

In our 20s and for the most part our 30s, we’re able to exercise through injuries and rely on our natural powers of recovery to do its magic. You're not so robust in your 40s, however, so you need to adapt your mindset, otherwise you run the risk of developing a chronic injury that you won't be able to shape over the following years and decades.

Listen to your body, never exercise through an injury, and if you're tired, rest. And if you do start to get a ‘bum knee’ or ‘bad shoulder’, get it checked out by a doctor. Even the most inconsequential injury can become permanent if ignored.

What you should be eating

What you put in your body becomes all the more importance come mid-life. Healthiness now isn't as simple as looking in the mirror and looking at the scales: you can be an outwardly fit, slim person and still harbour gremlins inside that will take their toll later in life.

Fortunately, it's not to late to correct years of over indulging on fast food and quick snacks. Stick to these easy rules and you should ensure that your diet works for you rather than against you...

6. Stay hydrated

Did you know that almost any ailment is at least slightly alleviated by a high water consumption?

This is because a hydrated body is our optimal and natural state of health, helping to flush toxins, reduce inflammation, lubricate joints, support your metabolism and improve energy, digestion and mental performance. Often you'll get a noticeable increase in health and vitality just from upping your water intake alone.

It’s absolutely essential to stay hydrated if you want long and lasting health. Don't like the taste? Get over it! Water is your life source.

7. Eat a balanced diet

We could get really complex on this one, go into all the various diets out there and calorie counting apps and fasting theories. But it only serves to put a lot of people off – and to an extent, it's all just noise anyway.

Here's the one easy rule you can use instead: eat 40pc carbs, 30pc fats, and 30pc proteins. That should ensure you have enough energy for the demands of the day, take in all the building blocks for muscular repair after exercise, and supply the fats needed for optimal hair, hormone and skin health.

Of course, everyone is a bit different, and you can play around with that formula to fit your needs. But it's a good starting block for a diet that will keep you fighting into later life.

8. Eat a colourful plate

Seems trite, but it's true. Filing your plate up with several colours for every meal practically ensures that you consume a varied intake of healthy fruit and vegetables, which provide an abundance of vitamins, minerals and antioxidants.

The antioxidants alone will play a huge role in how well you age, as they help to battle damage from free radicals and oxidative stress. An increased intake will fortify your immune system, making you more resilient to illness and disease.

9. Get a micronutrient test

Micronutrients sounds like a complicated word, but realistically they're already a natural part of your diet, present in all (well, most) of the foods you eat.

However, as the body depends heavily on micronutrients like calcium, vitamin B12, magnesium, potassium and omega 3s, it's worth checking that you're not suffering from a deficiency.

To give you a sense of the damage a deficiency can cause, here's two examples (of many!)

B12. A deficiency can result in vision problems, tiredness, tingling sensations, and sensitivity to light. If allowed to continue long time, a lack of B12 is linked to a higher risk of breast and cervical cancer in women and Alzheimer's in men and women.
Selenium. Never heard of it? You're not alone. But a deficiency in this trace mineral, although rare, has been linked to impaired immune function, recurrent miscarriages, hypothyroidism, extreme fatigue, and low testosterone in men.

Ask your doctor for a full vitamin and mineral MOT – he or she should be able to send you in the right direction.

10. Avoid high Fodmap foods

Remember when I said we could get more complicated about diet in point seven? Well, this is one of those examples – and I promise it's more than just needless noise!

Fodmap foods are certain types of carbohydrates that cause a significant amount of abdominal distress for many people. Over 4 million people in the UK regularly suffer with IBS, and your chances of being affected increase as you get older. Reducing your instances of Fodmap foods and finding alternatives should help to alleviate abdominal bloating and indigestion.

Common offenders include: Onions, garlic,wheat, animal milks and apples.

11. Avoid inflammatory food

Inflammatory foods are foods that in many people create a swelling in the stomach. The body treats this inflammation as an immune response, expending energy to counteract it and lowering your immune function. Inflammatory foods that should be minimised include:

Dairy (excluding cultured)
Processed Meats
Gluten
Additives
Trans-fats
Preservatives
Refined Sugars

12. Limit alcohol and caffeine

Whilst alcohol and caffeine can certainly be enjoyed in moderation and, arguably, have significant health benefits at a low rate of consumption (red wine can help heart health and coffee beans are believed to lower dementia risk), it goes without saying that over consumption of either is going to have a negative consequences. For example, as you get older, your liver might struggle to clean your blood of alcohol with the same efficiency of its more youthful days.

So, don't stop drinking, but do drink with careful moderation.

Joint care
Past 40, you’ll start to notice wear and tear on some of your joints. This is normal – those joints have been in use for a while now – and not something to freak out about in itself. However, heavy training, especially hard endurance work like running, can exacerbate things, so it's an idea to focus instead on shorter, sharper training sessions.

In terms of nutrition, consider a couple of useful supplements – glucosamine and collagen – which can both work to slow and even reverse joint degeneration.

Gut Health
On thing you'll notice as the years roll on on is that your stomach is a little less versatile than it used to be. As we get older we tend to experience more indigestion and bloating. This will particularly be the case if over the years you’ve had a long history of antibiotic use, have been ill abroad or experience a lot of stress.

We're only at the very early stages of understanding the implications of maintaining a healthy gut microbiome, but studies have already linked the billions of gut bacteria that live inside us all to issues as far reaching as obesity, diabetes and depression.

Here are some simple tips you can apply at any age to improve your gut health pretty easily:

Avoid any foods you know you have a reaction to. Obvious, I know.
Chew thoroughly. I’m talking 30 to 50 times per mouthful!
Avoid drinking liquids shortly before or after eating
Avoid treating every instance of indigestion with over the counter medication. Instead seek to understand why the problems occurred in the first instance
Be wary of mixing fruits with other foods. Many people can handle this, but for others mixing fruit with other foods causes an almost instant reaction. This is because the foodstuffs are digested at different rate, putting a strain on your stomach.
Speak to a dietician or your GP about the use of probiotics or digestive enzymes if problems persist

Keeping the mind healthy

Slowly, we're coming around to the fact that mental wellbeing is just as important as physical fitness in terms of our overall health. In fact, the two are entwined: your mental state effects everything from your blood pressure to hormones and resting heart rate.

Remember that no training plan or diet is going to be completely effective if you are in a bad place mentally and emotionally.

Here are some easy rules to live by for a healthy mind ...

15. Meditate

A 2015 study found that even a very short regular meditation practice may be an effective strategy for counteracting the cognitive decline associated with ageing.

Just five minutes of sitting or lying while trying to calm your mind will help. Your stress levels will drop, your brain will breathe, you'll come out the other end more robust and ready to deal with challenges.

16. Keep up appearances

We are social creatures and whether extroverted or introverted, investing time and effort into our close social ties is crucial to our ongoing mental health.

Of course, it's easy to let old friends slide as you hit mid life, with the time pressures of family and work at the fore. But there's good evidence that our social ties are among the biggest determinant of our long term health. In fact, earlier this year a Harvard study found that the quality of our close relationships, be they community, social or romantic were often a greater predictor of our health in our older years than certain genetic and lifestyle factors that would commonly be thought of as the greatest predictors of health.

The study also found that social support helped protect both body and brain, helping to offset cognitive decline.

17. Have a goal

Finally, having a goal to work towards can do you the word of good. It focuses the mind; and perpetual ‘constructive discontentment’ keeps life interesting. You needn’t be super ambitious – even striving towards a small goal will give you motivation and, eventually, something to appreciate once achieved.

Why not start now by picking just one point from the above and trying to work it into your life? There's no time like the present!

Future proof your body: 17 things you need to do now to be healthy in later life