In HS, I usually ran about 8 miles per day (on the days when we did not have cross-country meets) and I never got muscular from all that work - just lean and hungry. Boy! could I eat back then!I gave up weights for the last year and a half because my hands were getting extremely stiff and sore. I'm considering starting again but, I'll be using lighter weights. I run 10 - 20 miles per week depending on how I feel but, it's usually closer to 20. My wife and I also go for 3 - 5 mile walks on the weekend also.
I'd spend a week or two with my grandmother every summer, and she'd try to "fatten me up". It didn't work. I'd go down to the shop and work with my grandfather (heavy-equipment mechanic) and learn how machines really work. That was a whole lot more fun than staying at home, but I really needed total immersion in that field to get good at it. He had a wrecker service, but when some had a skidder, bulldozer, or other heavy equipment stranded in the woods, he would tell them "bring it here". Pick-up and transport (even for big stuff) is low- profit.