One of the most talented poker players I have ever met was attempting to play professional online poker for a year. His intentions were simple, win X amount of money, then close the game client and he's done his “work” for the day. This player was no slouch, and in fact he made quite a living off of this. Whether his sessions were an hour, three hours, ten hours long, or even 20 minutes long, he reached his stop-win goal and ended his session. Yes, he had losing days, but to limit his losses, he put a stop loss on his sessions as well.
For instance, if he lost 30 big bets at the table (he played limit poker), he'd quit and come back tomorrow. A stop-loss limit is very important and I urge anyone that plays, even socially, to have a stop loss. In a limit game, if you've lost 30 big bets, chances are you're doing something wrong and need to take some time away to adjust your game before you sit back down.
Additionally, knowing the limit where you're worried about the money you've just lost is essential. At that point, instead of posting the next round of blinds, get up and go. Poker is a stressful game as is; added intense pressure due to monetary losses will only result in a loss of concentration, focus, and bankroll.
Side note: If you're planning on playing pro, make sure you know exactly what you're getting yourself into. My friend knew he had a big enough bankroll to handle a rough losing streak and still sustain his style of life.
Losing money during any day didn't mean he was in dire straits and winning his usual amount didn't mean the world to him, but when he was playing an incredible winning session, he'd stop at his limit when he could've won much more. He always played great poker, but one comment continued to echo in my head: “How could you leave all that money on the table?”
One day I watched him play over his shoulder. He was dominating the $10/$20 tables for the first 10 minutes, he started out on a really nice rush and wasn't looking back. He had each player at his table figured out to a T and knew the raise was coming even before they were going to act. After all, he had played with them day after day and picked up on their betting patterns. Twenty minutes later he reached his stop win limit and I sat there wondering how he could do it to himself! How could he walk away? Those fish were all his! I wanted to take over, but thankfully he was smart enough to deny my request.
His logic was that if he reached his stop-win mark he'd be content for his day and continue adding profits to his bankroll. He wanted to be consistent, proving to himself that he could do it for a living. He would move up in limits when his bankroll grew, but was in no rush. Was his logic wrong?
No, but if you are a poker player looking to generate income from the game, you can't make the mistake he did. If you're running well, you need to continue to play as long as you are playing optimally to generate as much income as possible because you won't know when the next time a rush like this will hit.
Yes, he'll play against the same players tomorrow, but a river here and a river there will hurt even the most skilled players with deep bankrolls. I always asked him if he would continued to play, generating big wins day after day, without a limit and keeping his stop loss. I figured that he could've moved up limits every month if he wanted, but he was patient with his bankroll and let it grow itself.
Although he was a successful poker player with flawless negative bankroll management, he wasn't much of a risk taker which resulted in lower profits than you would expect out of him. Take advantage of the good streaks and don't leave your opponent's money on the table. Make sure it ends up exactly where it belongs, in your pocket