my biggest weakness is that i tend to lose my composure when the variance favors my opponent on the turn or the river. to remedy it I fold all my hands the time to regain my senses but that prevents me from staying focused and playing my A game. at the moment I also find it hard to stay patient at the end of the game, especially when I'm short stack.
I remember satelliting into a live $1100 main event at a local casino (second biggest buy-in I've ever played) and getting a read on one player early in the event. After a few levels I was heads up against him and correctly jammed on a flop of 569 rainbow with AA and the guy called with 88 in an ~100bb pot. Turn was an 8 -that tilted me for weeks.
I find losing in live poker is more tilting than online, since you dedicate more time and energy into it (commuting, registering, waiting for live dealers, etc...).
My biggest weakness in the game is that I think poker is not a serious business. Therefore, I can not boast of special achievements.
Keeping poker as a fun activity. Not getting sucked into the poker player paradox of, "the more I play the more I'll win." It's not about winning, it's about enjoying the time spent playing.