Their are certain limits to which are human strength can reach us. We may seriously want to stop something but relying on the arm of the flesh we are likely to face disappointment. The life we live is more spiritual than physical and only those who rely on the spirit make produce significant results.
One good thing we believers have is that Christ did not leave us helpless. He left us with the Holy Spirit. The Holy Spirit is our strength in times of weakness. Before we experience change outwardly it has to first begin from within. We can't experience true change if we haven't been transformed from within.
When we allow the Holy Spirit to take over we become repellant to sin. We'll be less focused on fulfilling the desires of what our flesh craves and be more desirous of fulfilling what the spirit desires of us. The nature of our hearts is what determines where the direction of our hearts will tilt to.
If we have a hardened heart it will resist the Holy Spirit to live and function through us properly. So when the Holy Spirit comes to dwell in us what it does first is to break our hearts till it becomes malleable and receptive to Him and Him alone. By doing so we all Him to have full expression over us and we no longer struggle with the hold of sin
We can only stop doing bad things with the help of the holy spirit.