Draining energy: Sometimes when we get a position and attempt a move it can be rather frustrating when that move doesn't work as planned. Don't get upset – remember that there are two games going on here simultaneously – the obvious one is to apply a move or series of moves to completion, the other is to exhaust your opponent physically and mentally. Each time an opponent resists a move from inferior positions he gets a little more exhausted. As long as you're winning that battle it's ok to fail with the application of some moves. Have faith that each time an opponent resists he's drained a little more from his batteries and there will be a threshold where he won't be able to effectively resist the next move.
