I played competitive chess in high school, and those games taught me 3 things that have carried me through life and love: first, you must kill your opponent until he's dead; second, don't make a move unless you mean it; and third, mercy is for God, because your opponent has none. Too cynical? Get a clue.
Chess is a great game. People love to compare OTHER things to it: boxing is like a chess match; litigation is like a chess match; romance is like a chess match. Chess, however, is not like a chess match. Chess is a locking of intellects, an imposition of your will on your opponent. Even more than wrestling, or MMA, chess involves the wills of opponents as directly as possible. And from that contest, you can take away experiences and strengths that you can use in other situations that involve an opposing will.
First, you must kill your opponent until he's dead. The game of chess ends when you checkmate your opponent's king or your opponent resigns. Until that happens, however, your opponent is fighting - desperately - to prevent that from happening. The more you are winning, the more desperate will be the fight. I remember watching my opponent scan the board, searching for that one move to stave off defeat, and then making a shocking or unexpected move. After searching for the motive, I would realize that my opponent had laid a trap, usually a gambit (an apparent offer of a piece or attractive position) that appeared attractive but would lead inexorably to loss of material or position for me. I would ponder what my opponent was thinking as I avoided the trap and continued the pressure, the slow move-by-move tightening of the noose. But the strategy had to be driven home, sidestepping or thwarting every last-ditch attempt to prevent the inevitable.
Second, don't make a move unless you mean it. Tempo (time) is one of the most important elements of chess: it determines who has the momentum; it can decide your fate (or your opponent's) by making your piece arrive one move too late. The best way to keep the tempo on your side is to make sure that every move advances your strategy. Also, each move should be threatening to your opponent, should force him or her to respond. Otherwise, if your opponent feels no pressure, that is just more time to think about how to hurt you.
Third, mercy is for God, because your opponent has none. This is the other side of the coin from the first one: your opponent is trying to kill your king. Your opponent won't let you take back a move, won't let you take a second move, and won't let you back up the board a few positions. You make a weak move, and your opponent is on your throat, strangling you. You fall for the trap, and your opponent will execute and close it - and won't give you back the piece he is now up.
People will tell you that you can learn these lessons from other sports, or other business or legal activities. But few sports offer the immediacy of chess - you fail on 1, 2, or 3, and you die. Few activities offer the context of chess - there is no availability of an external excuse. The game is you and your opponent. You don't win because the pieces were bigger, or the weather was too wet. You win because you locked your will directly with your opponent's - and you prevailed. Take that lesson to marketing, litigation, business, or landscaping. And win.
