The same thing happens to me. I am just starting to worry that "I don't mind not growing as old" is not the worse case scenario here, as you are implying. Apart from not growing as old, you may surprisingly fall into a situation where you can't do some activity even while young. I just screwed up my knee while jogging and it seems to take months to recover. The first day I couldn't really walk, and then the next 3 weeks (and counting) I cannot run. And I blame my sedentary life and plain lack of care during the previous decade for this. The consequences of living unhealthy are just often underestimated. It's not just about living to be older, it's also about what happens in your mid-life.