everyone is different, even if I'm biking/walking everywhere and working outside, I still need to work myself to exhaustion if I want to get any sleep. I currently train muay thai, but even when I was young and doing yard work for a living I still trained with my friends and played sports. heck, growing up my life was american football training during the day and after school, regular football a couple of times a week with friends, running around for fun, and then doing heavy yard work at home and at neighbor's houses on weekends.

Not that your's isn't valid, some people (like me) have a big surplus of energy that needs to go somewhere and sometimes the best available outlet is lifting weights.