There's a neat chapter on the power of the mind in Arnold's Encyclopedia of Modern Bodybuilding. In it, the stacked Austrian reveals a glimpse into how he engineered his rise from unknown to world figure.

The idea that struck me as port-able into our everyday lives was a mental distinction he made when talking about lifting. He advises the bodybuilder to put their mind into the muscle, and not on the weight.

Fully extrapolated, Arnold is talking about keeping your effort, your will, inside yourself and your ability to acomplish the task, as opposed to abdicating it to the obstacle.

Think about it for a second. By concentrating on your effort [muscle], you are centered in your capacity, instead of focusing on how hard the task is in front of you. In short, this is a solution-oriented versus a problem-oriented focus.

If you maintain this focus, at the end of your session, or work day, you can rest easy, knowing you put your full effort in, instead of letting your energy bless out into anxiety about how hard your workload was.