Thinking about one's demise, or that of someone close to us, is unpleasant and I don't think it should be dwelled upon. Acknowledge that it will happen, and move on with life. But people just don't at times. They become weighed down with unimportant things, fail to take advantage of the time they have and then regret it later.
Your parent story is tragic, I'm sure one that has been repeated around the world. It's a good reminder that spending time doing those things that provide value is the best policy.