How do you learn on the job?

Grit and blood and spite.

You find that when you've reach the bottom of the barrel, you haven't because it actually goes a lot deeper than you thought it would. You are capable of magnitudes more than you think you are. It's only when you're in a situation where failure is not an option that you discover this.

In the first world, we have it so incredibly easy that most of us never discover our true potential.

First, that sounds normal, and it's fine to encounter this feeling. Facing unknown challenges is a big part of creating new value.

Next, it's time to take a day and spend some time planning. Bring clarity to what your goals are for the next couple of months. Having a small set of clear priorities, allows you to ruthlessly defer and minimize everything that isn't absolutely necessary. It's less overwhelming to deal with only 1-2 things like this at a time.

typically i try to learn one thing at a time before starting a project with 10 things I don't know well.

I’m feeling overwhelmed with having to overcome learning curves at every step.

In adult life, that's what learning feels like because we stop measuring ourselves against standards set for children.

Learning is doing things badly and knowing you are doing them badly.

Good luck.