Why do people go on strict diets to make themselves live longer?

[MrHT]

This has always bugged me for a long time. People restrict themselves of junk food & fast food just because they want to eat healthy and live a longer life. But think about it. Wouldn't it be better to live a shorter life and enjoy it rather than live a longer, miserable life? Now, I'm not saying to order 10 donuts at Dunkin' Donuts and gobble them all up, but once in a while, enjoy yourself!! Some people restrict themselves and starve themselves all their lives just to add more years to their life. But what good are those extra years of living if you're just miserable??