This is a very hard question, but i think you must set you 2 limits.

1. The time limit. You set you a limit of 1 hour and you dont play not more than this 1 hour.

2. The winnings. You must set a winnings limit for example of 200 Dollar. After you won this 200 Dollar you dont play anymore this day.

Because without these 2 points it will be hard to stop imo.