I will attest to all of that. Exercising feels great, your self-esteem goes through the roof, and, in my case, it just makes moving around (like, actually moving one's body, squatting, bending over, walking, running, etc), much, much easier.
Hm. I'm about 5'11" (~1.8m) and I weigh about 65kg (that's about 143 pounds), and have never had difficulty moving around, squatting, running etc. I typically climb stairs (e.g. multi-story stairs at car parks) by running up two at a time. But I've never had a day's deliberate exercise in my life outside of school; though historically, I've used walking and cycling a lot as means of transportation. I've never owned a car.
I'm 1.90, 92 kg (about 18% fat) and, although I also go up multiple flights of stairs two steps at a time no problem, I used to have a bit of trouble squatting comfortably, as my knees would hurt.
A month of squats at the gym later, I feel great. Half of it might be good technique, but my knees no longer hurt or crack...
