1. Keep reducing the goal until it's no longer scary. Instead of "learning X", maybe try "reading about X" or "try X for 10 min". Keep taking more off your plate until you feel that "I can do this" feeling.
2. When a fear pops up, respond to yourself with "I know". For example: "I might waste my time and never get good at X" -> "I know". If you repeat that process some contend that by giving your monkey brain (or flight response) attention and respect it starts to diminish. It just wants you to know how risky it thinks this activity is and can keep repeating or getting louder until you acknowledge that it's been heard.