It's very likely that those are just excuses.
And it's very likely that you're just afraid of yourself.
That you're afraid that you're not as good as you think you are (or that you're actually as bad as you think you are).
That you're not able to commit.
Or that you're going to quit.
But if there's someone or something you shouldn't be afraid of it's you.
Because it's the only thing that's not out of your control.
So what are you still afraid of?