I think exercising only for weight loss is waste of time.
But ...
Exercising for maintaining bone density, staving off dementia, socialising, increasing strength, feeling good, ... is an excellent idea.
And don’t forget there are many ways to exercise not just going to the gym, running a marathon or other activities some people hate.
Walking to and around the shops is exercise, dancing is exercise, gardening is exercise, housework is exercise (although I’d rather go to the gym), ...