The number one reason why you must do the things you fear is that you will kill the fear. Mark Twain once wrote, " Do the thing you fear most and the death of fear is certain."
That one reason alone is enough for doing the things you fear.
Apart from sending fear to its grave, you will gain something important. Something that many lack but desire to have. Self-confidence.
By doing the things you fear and by finishing what you have started over and over again, you self-confidence will take-off and soar.
By doing the things you fear, you will realize that most of the times many of your fears were unfounded and even those things you perceived as real were not that scary after all.
Go on now, face your fear and kill it.