"And let us not be weary in well doing: for in due season we shall reap, if we faint not."
The Christian life is meant to be a struggle. I think we sometimes get tired of the fight, which is why we settle into comfortable lives that aren't designed to put us into difficult or faith-stretching situations. The trouble with not experiencing pain and not embracing frustration is that you're choosing to stunt your spiritual growth.
Burnout is also a very real thing in Christian living. I have gone through periods of my life where I was literally spending five or six days a week at church or around church people. While it was certainly a very fulfilling time, after a while I began to realize that my righteous acts weren't bringing me any closer to God, and in fact were just wearing me out. While it can be very tempting in those times to simply throw up one's hands and take a personal and spiritual vacation, the much harder and more rewarding choice would be to renew one's dedication to the work, albeit perhaps with a more intentional focus on certain activities.
When this young man heard that Christians were being massacred half a world away, he could easily have shrugged and said to himself, "I served my time in the military, it's someone else's turn to do something about it." As we can see, he decided instead to make the much harder choice.