This is an example of a self invalidation born out of fear and failure. It does not create too much zest for living does it? I am very familiar with “I can’t” as it is a victims plea to the masses of helplessness.
What do to? Swallow the fear and jump in of course after some due diligence. What is your life to be? A pile of “I can’ts?” Or a bit of risk and learning. I know it all sounds too much like rah, rah you can do it. It is not, it is merely a negotiation with yourself.