Ever notice the voice that plays in your head after something happens in your life? You set a goal. You make it. What do you say to yourself?
You set a bigger goal. This time, you don't make it. Now what do you say to yourself?
Are you setting goals that you know you can make, just so that you can avoid hearing what you'll say to yourself if you don't make it?
Without developing our tolerance for the risk of failure, we cannot stretch ourselves beyond the limits of what we've (a) accomplished in the past, or (b) been told by others that we're capable of accomplishing. This mindset leaves us with only the possibilities that have come before, and limits our ability to imagine brand new possibilities that have yet to come.
Start by paying attention to and noticing what you say to yourself in response to the things that happen in your life. Find out how you're motivating yourself, and imagine how this might change.