It doesn't have to be about weight loss, it's about using your body! If you want your body and mind to be working at their best, you need to use them.I stopped exercising, because I didn't even lose 1 lb after 3 months.
Your body won't work properly if you don't push it, I guess like a car, it needs to be maintained if you want it to run smoothly and not get rusty.
Of course, if you don't have a sedentary lifestyle, then you won't need to do so much exercise as someone who sits all day.