Courage is the most important of all the virtues, because without courage you can't practice any other virtue consistently. You can practice any virtue erratically, but nothing consistently without courage.
Never lose a holy curiosity. Try not to become a man of success but rather try to become a man of value. He is considered successful in our day who gets more out of life than he puts in. But a man of value will give more than he receives.
The delights of this life are not its own, but our fear of the ascent into a higher life; the torments of this life are not its own, but our self-torment because of that fear.
An enemy always represents a weakness. This might be fear of physical pain, but it could also be a premature sense of victory or the desire to abandon the fight because it is no longer worthwhile.