Free Trait Theory holds that people can, and regularly do, act against their natural temperament for the sake of "core personal projects" they genuinely value — an introvert can convincingly perform extroverted behavior for a cause that matters enough to them, and vice versa. This is a genuinely useful reframe: temperament isn't a hard ceiling on behavior, it's a default setting that can be deliberately overridden for good reason.
The theory comes with a real cost that has to be managed, though: acting against your natural temperament, even for something you value, draws on a limited reserve, and sustaining it without adequate recovery time can produce real burnout — meaning the skill isn't just performing against type, it's knowing how to build in recovery afterward.
Brian Little, a self-described extreme introvert, became a beloved, high-energy public lecturer at Harvard, drawing on carefully developed bathroom-hiding routines and rehearsed excuses to recover in private between demanding public performances. His "Free Trait Theory" holds that people can act against their natural temperament in service of personal projects they deeply value — teaching, in his case — but Little's own body eventually gave a stark warning about the cost: overextending himself without enough recovery time led him to develop double pneumonia.