I'll give you a quote from David Sklansky's Theory of Poker.
You may occasionally be in a game where the best strategy is to win as many pots as possible, but such games are exceptions.
In most games the , bets you save are as important as the bets you win, because your real goal is to maximize you wins and minimize your losses.
Ideally, you want the pots you win to be as big as possible, and the pots you lose to contain nothing more then your ante.
You must remember that reducing losses-by not making the calls, for example, that a weaker player would make-adds much more to your win when the game is over.
Many players don't follow this precept, however obvious it may seem. They play as though they want to win the pot, an individual pot, at all costs. The worst of them, to put it bluntly, are suckers in the game.
On the other hand, a good player develops the patience to wait for the right situations to play a pot, and develops the discipline to release a hand he judges to be second best.
Thus, whether you are winning or losing on a given night is not in itself important, and above all it must not affect your play. It's easy to get steamed, or disgruntled, or discouraged, when your losing.
However, you must be disciplined enough to play every hand correctly, regardless of how you are doing.
Making money is the object of poker, and making money involves saving it on bad nights, as well as winning on good nights. So don't worry about quitting a loser. If your getting in with the best of it, you will win in the long run just as surely as a roulette
wheel will win for the casino in the long run.