Rant- eating healthy, money & death

Ok, so here's the thing, my wife is constantly going on about us getting fitter and eating healthier.
Sure i want to be fit enough for general life and to be around to play with my grandchildren, but at what point is to much, because if you spend your life eating healthy and staying fit, theres a good chance you will live long, and living long means you need more money. I know i don t want to have to work until i am 80 just because i have been fit and healthy and am going to live until i am 100, and i don t want to retire a 65 and be broke by the time i am 85 with another 15 years to go.
When do you say stuff it, with eating health and depriving yourselve of food you love & working out 3 or more times a week?
I know my parents and grand-parents did not have such a focus on these things, so why do we?
and if this mentality has grow over a couple of generations then how what kind of monster will it continue to grow into for future generations?