Concentrate on a game when your 3 year old is kicking your ass and your wife is chewing it.
What is the hardest thing to do in chess?

Not giving up when down in material....
Remembering all of the rules for Queen and King vs. Queen and Pawn endgames to avoid a draw (or to force it if you're on the other side)....
Probably the endgame in general....

It's without a doubt to force yourself to check every possible move. of you and your opponent. no matter how dumb it seems for you.

Isn't there another forum topic that says the same thing?
edit: yup, it's at http://www.chess.com/forum/view/general/what-is-the-hardest-thing-in-chess

How about bringing yourself to study? You set out to study the openings, endgames, etc, and end up playing 1-10min blitz online 8 minutes later lol.

Isn't there another forum topic that says the same thing?
edit: yup, it's at http://www.chess.com/forum/view/general/what-is-the-hardest-thing-in-chess
I guess I figured that there was another topic on this subject.
I would say that it is to make a move of deception that loses a piece or temporarily appears to give your opponent an advantage, hoping your opponent doesn't figure out your plan and turn it to their advantage.

I would say earning a FIDE title. Winning is pretty easy if you choose the right opponent. And it doesn't take long for an intermediate player to learn the N+B mate.

How about bringing yourself to study? You set out to study the openings, endgames, etc, and end up playing 1-10min blitz online 8 minutes later lol.
so true!

Ive always found beating the worlds top GM's without losing a piece pretty tricky. I only manage it about 3/4 of the times I play them.
No matter what rating you are or your opponent is, no matter what time limit there is, there has to be something that stands out as the hardest thing in chess. I would say winning is the hardest thing, but I would like to hear other opinions.