Poker is not for the faint of heart, but it is for those strong of mind. Many facets of the game, such as bad beats and downswings, can wear negatively on your poker psychology; whereas, things like heaters, getting lucky, and winning a tournament can do wonders for our state of mind.
Variance in poker means that there are things out of your control. You can get your chips in preflop with pocket aces, but that doesn’t mean you’re always going to win. All you can do is play your best and leave the rest up to the poker gods.