Ok, let me elaborate, and keep in mind, this is only my opinion, I could be wrong, but this is what have been working for me until now.
The thing about thinking too much (not only in art, but in life too) is that it can easily drives you to depression or conflict. All the insecurities start to float around you, and become overwhelming. Because, as you well put it, perfection is impossible to reach, and there will be always someone better than you.
You have to give just a thought, so you can develop a plan. But not staying on the thinking part. Better put, don’t allow the thinking to put
The plan is so you can have a map of where you are heading, and can concentrate on the way once you start running. And no began to wonder where you are and what are you going to do in the middle of the road, so latter, you’ll end up in a corner of the woods, crying on a fetal position.
In my opinion, the way to fix that mindset, is to stop thinking and start making little goals as you go on the way. In that way, you will be felling more motivated every time you reach a new goal. That is better to aspire to something gigantic from the scratch, in that case the pressure would be unbearable.
Another thing, being depressed comes with being an artist. Artists are unsecure all the time. And again, not only with their art.