Questioning the nature and implications of liminal instances necessarily involves failure, if only in the specifically technical sense of entering spaces where prevailing criteria of success scarcely apply.
Are you bored with life? Then throw yourself into some work you believe in with all your heart, live for it, die for it, and you will find happiness that you had thought could never be yours.
Mostly I do Iyengar. I like anything that's hard enough to make me cry in class. I like to be pushed over my limit and broken down a little bit.