"What is the part of me that is preventing me from moving forward worried about?"

Be careful not to be antagonistic about the answer. The goal is to make that part of you less worried, thus making you more productive overall, not just on your blocked task. The roadblock is telling you something that you haven't yet explicitly acknowledged, so acknowledge it, thank it, incorporate it into your thinking, and resolve it.

Example: "I'm not smart enough to solve this math problem." Worry: "I would need to learn a textbook's worth of math right now in order to solve it. I must go learn it now." Resolution: "It's fine that I don't have the ability to solve the problem, and learning the math in 5 minutes is impossible and not necessary to satisfy my goals here. Trying to solve it the best I can will help me learn the math for future problems."