What does not kill me, makes me stronger.
For Nietzsche, psychological growth is one of the most important things there is. Experiences do not have to be pleasurable to be good for us. Often it is suffering which gives meaning to our lives. By gaining experiences, good or bad, we grow as people, so long as we survive them, of course.
This quote is usually said as a quip, rather than to understand it’s true meaning. Navy Seals fully understand this and what it takes to not give up even when you want to and it is the easy path to take.
File this under the school of hard knocks, of which I have a Ph.D.
Delusions of Adequacy 