You are full of wonderful possibilities. Do something with them. The most painful regrets, those which never go away, are regrets of things not done, things never attempted.
Stopping before you reach the goal does not make the discouragement go away. All it does is make the discouragement permanent. Instead, keep going, keep making the attempt, until you make that last, fulfilling attempt that brings the success you desire.
Doubt is merely a thought. When experience proves it wrong, it will quickly go away.