I live in a retirement community, see a lot of old people and fish with a few of them, at 62 I'm still considered to be a "young feller".
You hardly ever see old fat guys out on the lake, old skinny guys, yes. I want to fish for as long as I can, and to do so, I need to lose some weight. Being old and fat is not good, yeah you might still live a long life, but it's tough to get out and do things. In short, quality of life will probably be better as you age if you keep yourself in reasonable shape.