Guessing you're in good health, have some control over your working hours, and are able to maintain a pretty clean sleep/wake cycle. 7 quality, consistent hour

Guessing you're in good health, have some control over your working hours, and are able to maintain a pretty clean sleep/wake cycle. 7 quality, consistent hours of sleep is plenty enough for most people, sure, but that means being able to shut your eyes at 9pm to get up at 4, which means having the discipline and energy to get ~everything necessary done by say 8. Avoiding alcohol def helps there. People in their 60s/70s don't have kids to look after, and in many cases don't have to work full time. For those that make it to that age with themselves and their partner in adequate health, I agree daily exercise is a sound investment.