If you see it arising, let it go. Don't take it in. If you are careless and let it sneak into the heart, then as soon as you are aware that discouragement has snuck in, you must immediately get it out. Don't let it feed on the heart. Otherwise it will become a habit, and you will become weak and debilitated, upset over every trifling mistake.
Discouragement is an enemy, an obstacle.
It makes the mind restless and the nerves disordered. The brain becomes dull and murky. Discouragement is a bad habit, a block to clear intelligence and discernment. We must practice putting the mind back into shape. Before we do anything, while we're doing it, and after it's done, we have to practice keeping the mind cheerful and bright, with a constant sense of well-being.