The problem we face is down to the fact out success in poker, and therefore our failures, are measured in monetary terms. We look at our result and see we are up a certain amount of money or down a specific amount and base our thoughts on that particular session on that figure. If we finished in profit then the session must have been good and if we lose money then it was a bad time at the felt. But it is not like that because sometimes the opposite is true.
You see, in poker you have to make plays that are going to yield profits in the long run and not focus on the short term results. If a poker player came up to you and offered you 3/1 odds on you winning a hand of poker where you hold a pair of threes and he holds ace-king of spades then you should bite his hand off and see if he will offer to play the hand thousands of time. This is because your pocket threes are around a 55% favourite in the hand, which is a small margin I will admit, but over a significant sample size you will come out on top by quite a margin, even if you will lose quite a number of the all-in confrontations.
By continually making plays that will yield profits in the long run you will succeed in poker but be aware that the long run is probably much longer than you give it credit for. Do not get disheartened when you miss yet another flush draw despite having the right odds to chase it because it will come good in the end. Embrace the fact things never run smoothly in poker because it is this roughness, these blips on your graph, that keep the weak players coming back for more and more action.