The thinker is one of the phases of existance you might get trapped in. This is when you spend your time just considering your next step with-out actually doing it. You read and research, and maybe even discuss and debate, but never take action. You might say, "I am not ready yet. I need to do more study. People will make fun of me. I'll be a laughing stock! I am not qualified." Self doubt fills you in this phase.
The way to get out of this phase is to start small. Do something small to learn that you can do it. Once you succeed or fail, note down the things you learned. Then try again with something a little bigger or more complex. Keep trying and growing. Make sure you get feedback from your mentors. Work on one thing during each practice, and focus on it. Then afterwards review the results. Don't try to change too much at once. Focus on only one improvement at a time.