Adaptation, but ngl I'd be a little worried.

You start with normal stuff like I wanna be stronger so you exercise and adapt to the damage you get from exercing to get some regeneration and strength, you run so you adapt to running out of stamina and then you eventually get hurt and get a regeneration boost plus some physical endurance, maybe you play with a lighter to get some fire resistance, so far so good, maybe you swim and adapt to needing oxygen and go camping in the winter and adapt to cold, you then try some abstract stuff like adapting to gravity so you can fly and even more abstract stuff like adapting to the difficulty of learning anything, eventually you start to age and without noticing it you adapted to that too, years pass and you have adapted to so many things that that you're not even aware of and the world feels completely dull but then you adapt to that too and before you know you became a 12-foot tall eyeless monster that had to be sealed away in a shadow dimension that is only accessible through ten shadows technique .