Are you perpetually a student?
"You are always a student, and never a master."
I believe that quote is supposed to be an empowering phrase to always keep learning, but it misses something fundamental. It doesn't allow us to recognize the progress we've made.
See we may always be students, but we also are always teachers and builders.
If you don't take the time to acknowledge your abilities, you will always shortchange yourself. You will never give yourself the credit you deserve. Even when you absolutely crush a big project at work or at school, you still have this feeling that you're not good enough. You start to think things like:
I'm still a student, I can't work on my craft and gain experience while I'm learning.
I can't take that job or this position -- there's still more to learn.
I shouldn't teach someone something or else I might teach them something wrong -- we should wait until someone more qualified can teach it.
Being unable to put yourself in the teacher/builder mindset is a byproduct of the school system. In 12 years of constant student status, no one expects anything of you. For some reason, you're not expected to build anything, or teach.
You're just supposed to sit in class and shut the hell up.
Being a student is healthy in small doses. It keeps you hungry for more knowledge.
But without equal parts of you acknowledging your successes and progress as a teacher + builder, your confidence will never be built. You'll let opportunities pass you by because you're not "ready".
If you want to gain more confidence, start teaching more people what you know.
Start building without someone telling you to.
Don't wait for permission -- just do it.
In primary school, the reason we never feel the need to teach is because you are mainly interacting kids your same age, and same skill level. You hardly ever get the chance to mentor or teach a peer.
Because of this, you are in a perpetual state of never being really good enough to teach anything. You never get the chance to show someone what you know as you rush to the next subject to be mediocre at.
For 12+ years, the school system is instilling this habit of being a perpetual student into you.
And start creating.