Strongman

From LSWiki

 Strongmen are possessed of a simple, straightforward psychic talent: the
ability to use psychokinetic force to tremendously increase the effective
strength of their bodies.  Often the use of this talent is nearly unconscious,
and there may be people with this talent throughout the land who think they
are simply heroically strong, not psychically endowed.
 To boost your strength, concentrate on mentally assisting your strength;
concentrate on ceasing to mentally assist your strength to allow the
psychokinetic force to lapse.  Your level of ability as a strongman is
determined by your willpower and your skill at psychokinesis.