Those who cross boundaries. William Blake with painting and poetry. Yue Fei with martial and poetic arts. Rabindranath Tagore with music and poetry. Da Vinci with painting and sculpture. Weird Al with accordion music and comedy.
Mind control. I can control my mind with my mind.
[NOTE: I’m not sure what “secret” has to do with it. Anything one blabs across the internet is — by definition — not a secret. Though the skill I mention takes place in a purely subjective realm, so — in that sense — might remain unknown to the general public.]
I’ve been learning to juggle. It’s an excellent skill because you have to fail a million times before you can be successful, and you can’t partially fail or fail in a controlled fashion. It’s kind of all or nothing. So, it teaches persistence and to be less prone to becoming demoralized. It also teaches one a lot about how one’s mind works at the speed of instinct.
Tiger Riding for Beginners 