All spell casters gain their abilities through a form of demon possession. So in order to gain magical abilites, PCs must track down and trap demons. Of course there are some pretty powerful demons, if the demon is stronger than the PC, the PC could find themselves subjugated to the Demon's will.
A certain culture has a curious pass-time- muscle art.
Muscle artists (who are called by a special name) work hard to sculpt their bodies, trying to become as muscular and buff as possible. The best among muscle artists look almost grotesque in their amazing muscularity, Atlas-like giants with shiny, oiled iron arms and legs.