Don't let fear of not being good enough, slow you down or stop you.

You need to be confident in your ability to do X. If you are anxious about being able to do X, if it feels uncertain, it will be hard to fully commit yourself to do everything that you need in order to do X.

Watch out for people giving you negative reinforcement, e.g. by saying that what you did sucked. Watch out for self-deprecation, feelings of inadequacy. Don't allow seeing someone very competent, to make you feel "I will never be able to get to this level, let alone surpass it." Don't allow any of these things to make you aversive to doing X.

Find that certain kind of confidence of "I can do this!"

Yet, never ignore the ways in which you can become stronger. Destroy that certain kind of smug confidence that makes you feel superior over the ones weaker than you. Destroy that confidence that tells you "Look at me, I am so good." Only measure yourself to yourself. How much better did you get to you-one-year-ago? And how far are you still from the ideal version of you?

Maybe I have overdone the poetry a bit. My basic point is that you want to be confident in your own abilities because there are lots of harmful psychological consequences that come from not believing in yourself. But at the same time, you should also watch out for the ways in which confidence can hamper your growth, e.g. when you don't see ways in which you can improve, because you are too busy thinking about how great you are.