You can’t become great without first being less-than-great.
No one was born composing symphonies; no one was born with a great two-hand backhand, a mastery of juggling, or the ability to make a perfect Hollandaise sauce that doesn’t break.
The great people in any skill started out as newcomers, too. So understand that there’s a path from where you are now to where you want to go, and that probably the most significant barrier is time.
Practice.
We’re almost all so afraid of having a dream and failing to reach it that we will fail to see that everyone who reached their dream started out at the beginning, too. Literally everyone who can do what you want to do was once where you are now.