Some of them are actually kind of painful. Some of them make you realize things that you really didn't want to. They require you to face some hard truths. You then have to deal with those hard truths, figure out how to carry them or get rid of them, like an awkwardly shaped piece of luggage. Some epiphanies force you to change the way you relate to others, even when you all you want is the exact opposite.
But because they are epiphanies, there's no turning back...you can't unrealize an epiphany.