Most people probably feel this at least once in life. 

You're just average, and that's a problem.

You're not good enough (yet) to hold a high ranking position at work, yet you're good enough to NOT want to simply settle for any random job. You're stuck in the middle and then you think, where do I belong? Did I study so hard to graduate and lead this average life?

It's made worse if you still haven't figured out your calling in life. Probably some people never will. You just lead your average life in a moderate job in an acceptable way. Trust me when I say I feel this a lot. Nothing quite calls out to me and I'll lead my average working life probably for the rest of my average life. I care too little about the important things and I care way too much for the trivial things. 

Somedays you'll feel an unexplainable fear and you question yourself about being just average. You compare yourself against friends and family. You wonder why you can't be like them. You get jealous. And it just spirals downwards all the way in an evil cycle. You fear one day you'll go from being average to being forgotten.

Fear is your greatest enemy. 

When you can't come to terms with yourself, when you start doubting everything, and when you develop a fear, nothing in life will ever be satisfying. In that case, perhaps you are your own greatest enemy after all.