Accepting things in poker, or not accepting them, is important I feel, and has much to do with pyschological aspects of the game which affect your play. In terms of not accepting situations, a key example would be when you have just lost a big pot and are short stacked. Many players will immediately feel that all their hard work was for nothing and accept they will soon be going out of the tournament. So much so in fact, that they will simply gamble on the very next hand and push the rest of the chips in.
Whilst it is understandable to be frustrated in this situation, you have to try and think clearly about what pressure the blinds will put you under when they next reach you, and how long you have to attempt a double through.
Another point to consider would be those players that cannot accept they didn’t play a hand as they should have. It is easy to blame bad luck in poker, and this can of course often be the reason for your downfall, but if you wish to improve, you have to look at your own decisions first and foremost.
When luck does happen to be involved in you losing a big pot and you know you played the hand correctly, acceptance of the fact that these things happen in poker, becomes improtant too. There is nothing to be gained from dwelling on events that have passed, and so accepting you got unlucky and moving on with the game is imperitive to turning your situation around.
All in all, it is easy to play poker when luck is with you, but when things are going wrong, it is important to understand and accept the reasons why, and perhaps apportion blame to your own decision making, however much you might not want to.