Just today I suffered a loss. I topped up my account with $10 (knowing I'd lose it), so I played one of my favorite slots and after 5 minutes I had doubled my deposit.
What do I do? I put the $20 back into play and in less than 10 minutes I lost it all! I closed the page and continued with my activities as if nothing had happened.
Sure, we're only talking about $10; otherwise, it would have been $100 or more, but the idea is the same: learn to ignore these things, not give them importance.