Devin was always a skinny child. As he started to grow, he decided to fix this by working out. He decided to start with the weaker side (his left), then do the right after. He's hasn't got there yet.

Strength
Super-human level of strength on one side of body.

Strength Source
12 hours a day of heavy lifting. Devin also devised a special chemical concoction that helps him grow muscle more quickly.