These words frequently came to the mind of Viktor Frankl after he became acquainted with those martyrs whose behavior in concentration camp, whose suffering and death, bore witness to the fact that the last inner freedom cannot be lost. It is this spiritual freedom which cannot be taken away that makes life meaningful and purposeful. It may remain brave, dignified and unselfish. For the Christian, suffering does not intentionally make one bitter rather, suffering makes one better. Suffering is productive in that it produces endurance.
Endurance is the ability to stick with, to have stamina, to bear up, to tolerate.
The following story demonstrates how suffering can produce endurance. She practiced behind closed doors, so no one would interrupt her train of thought or make fun of the way she walked. Denise had been born club-footed, and even after several surgeries, her feet did not line up with her knees, and she easily lost her balance. So she practiced walking in between surgeries. She was seven at the time.