When the kid you tutor finally gets it, notice how long it took. Then give yourself the same patience.

Watching somebody else learn shows you the real timescale of learning, which is far longer than the one you allow yourself. You are patient with them through weeks of confusion and three wrong attempts, then turn around and expect your own understanding to arrive at once. The difference is not in the brains, it is in who is being watched kindly. You are allowed the same terms.

Next time you are slow to understand something, give yourself the number of attempts you would give a younger student. Say it out loud if it helps: this takes a few tries. Then take them, without the commentary.