If I can stop for a second and understand why I'm scared of the task (am I worried the best I can do won't be good enough?) I can employ strategies to work around that fear. One that's worked especially well for me is approaching a task as if I'm a complete novice. If I can pretend for a moment that I don't have years of experience, and start again from the very beginning, I give myself permission to make mistakes and "play" within the space. Approaching learning like a beginner, and letting go of any pretense around results or performance, seems to be the key to engaging in deep work for me.