Not enough programmers/founders/workers exercise this principal.

Our mind pushes us to believe that hours worked = productivity. But time after time this has been disproved when work is to be sustained over long periods of time[0]

Once you learn this; it will help you so much as a programmer.

TLDR If your having trouble with bug/feature - have a nap or go for a bike ride.

[0]: http://www.cnbc.com/2015/01/26/working-more-than-50-hours-ma...