We are all human. We all have fears of rejection in some form or another. This ultimately boils down to your ego / sense of self-preservation. Either let the ego lead or tame the ego and open yourself up to the possibilities. If you let your fears hold you back then you're guaranteed to not reach your full potential.
Sometimes overcoming the fear of rejection boils down to your perspective. If you think of a good day as a day you sold a home, then even if you're a great agent selling 40 homes a year then that's 216 bad days.
In this business, the quicker you learn to get out of your comfort zone, the faster you're going to be successful.