I've been thinking about this even before Fable came out...
Hero learns shadow arts
Hero finds out about this family that lives in the distant mountains that may have knowledge about ancient shadows arts, which basically consist of stealth, camouflage, espionage, bombs, weapons, combat, assassinations, etc. Yeah, basically ninjas, but we won't call them that, okay.
Hero goes searching for the place, finds it after spending a month in the wilderness, battling beasts and whatnot. He says he wants to learn the shadow arts, but the family head says it's not going to happen. Eventually hero convinces the family to teach him after he proofs his worth in a series of mental and physical tests. After the test he spends the next 10 years (gametime), learning various things (via actual gameplay, this ties into another idea about needing to actually learn to things you do) and finally returning home as a genuine shadow art master.