I don't exercise, but my school is a vocational one and I'm in the Carpentry program. We're currently building a home, and I'd say I've gained a fair bit of arm strength from it. Walls are damn heavy, as are sheets of drywall. I've also got a serious farmer's tan. My forearms below my sleeves are tanned, but anything under my shirt is pasty white. 

ai'll het yuh wit a hamma