This is very misguided. If you get old with no exercise and deteriorating health, it's gonna fall upon your family to take care and worry a lot about you. It's immediatist if not selfish (by not wanting to face the different kind of discomfort) to do as you say.

Being strong helps everyone around you passively and actively, with stronger effects as the decades pass by, and remember from other research that a strong body keeps a mind keen, with better blood flow for all functions. Sacrificing that is not being smart about helping people.

Last and less scientifically, if you want to heal your environment and community, first heal thyself. It's the only subject from whom you can guarantee cooperation.