I decided a few years ago that I play games to have fun and if a game isn't fun, I don't play it. I don't have much time these days to dedicate gaming, so I want to enjoy the time I do.
I've had a few I've really enjoyed until I hit some really terrible game mechanic or even a boss encounter I can't get past. I'll usually give it a few days/tries, but I'll flat out just bail and uninstall a game if it is causing me too much stress.
I've been bouncing around through various games I've already bought directly or ended up owning due to buying bundles. Just finished Call of Juarez: Gunslinger and am trying to decide on what to get into next.