What is your biggest fear?
A typical answer is death. If it is not death itself, it is the fear of a creature that could easily cause death: sharks, spiders, snakes, jellyfish, etc. The ironic link between these creatures that can cause agonizing death and death itself is the vast unknown of their living quarters (oceans and dense, unexplored forests) and the ambiguity of the after-life. Nobody ever knows when they will meet one, or both of these fears, head-on, so why fret over a scenario that tends to be impossible to foresee?
Another answer I have heard came from a woman, but men could fear this as well: Infertility. The inability to produce children. Technology has come far in this respect, having the ability to increase or help either sex as best as possible with certain procedures or experiments. But the thought of being unable to play catch with your little dude, or be your daughter's example of how a man treats a woman and vice versa, could really eat away at someone.
Next: Failure. Nobody has ever enjoyed failing, but from it come two avenues: 1. Get up, learn and attack the same problem or goal even harder. 2. Lay down, and stay down. Great success can come from the failure like a phoenix being born from its ashes.
It is not failure itself, but the disappointment in peers, that is my, and others, biggest fear. For the number of times I have been told I cannot or have failed, I can boast the same number of times I have succeeded in response to those particular troughs. Hence, failure is not my fear, it is the baggage that comes with it.
There is nothing quite like looking into the eye of someone who put their full support and belief in you, only for you to turn around and disgrace them in such a way that they are left with nothing but disappointment. Guilt tends to set in alongside penitence, catapulting anxiety and stress levels into the stratosphere.
Sit and reflect on it, examine it, and move on. What is great about disappointing someone important to you, is the chance to redeem yourself. Pull off redemption in spectacular fashion, and that disappointment will quickly turn into that sought-after faith we all wish someone would have invested in us.
Having this as the biggest fear is an eloquent double-edged sword. I hurt myself and those who care, but yet I am able to grow and become a better man in the process.