Results Don't Matter

This is a very simple concept every good poker player knows but it’s very hard to grasp for average human being. We all too used to judge performance by results and we are all too result oriented in our life. But the fact is result of a single hand of poker does not matter. What matter is who made a mistake playing this hand? If you make (bigger) mistake then your opponent you lose money in the long run if he made mistake – you profit from it in the long run. 
To demonstrate this concept lets look at a very simple game. We make a deal to flip a coin. You put $1 on heads and I put $1.10 on tails. Assuming coin is not rigged and your probability of winning is 50% it does not matter which side the coin lands on every specific toss, this game is profitable for you in the long run. 
Same with poker. Poker is not a card game. Poker is the game of making deals. And if you make more profitable deals then your opponents than you make money in the long run. Cards in poker only used to bring variance in the game so players who make bad deals could win sometimes and that keeps them playing. 
Not being result oriented also helps your mental game. If you concentrate on making most profitable plays and don’t care about results of each single hand you won’t be affected by bad beats. Because you know if you got bad beat somebody had made very bad (and very profitable for you) deal with you. And you are happy about it.