This is such a great story. In How I became a cartoonist, Tom Fishburne explains his journey from drawing cartoons as a side hobby to turning it into a successful business:

I then faced the terrifying decision of when and how to jump and leave a safe job behind to make it a real business. I found inspiration in a quote from David Hieatt: “There is a point on a runway during takeoff that a plane reaches V1 speed. Once it passes V1 it has reached the point of no return. The point where the take off cannot be aborted. The plane has to take off. Or crash.” He suggested that entrepreneurs draw their own V1 line, and then jump when they reach that point.

Here he explains how he dealt with one of his early setbacks:

When you do something entrepreneurial, sooner or later, you will wake up screaming. I discovered that I started to have pain in my wrist if I drew for longer than 20 minutes. This is a problem when you make a living with your hands. It scared me. I highly recommend that you never ever google any health issue you fear you might have. Fortunately, I was able to change my behavior by wrapping my pens in foam rubber, using ergonomic keyboards, and wearing a wrist splint. The pain went away. I learned that any setback is just a test to see how badly you want something.

There is so much honesty and wisdom in this essay – you have to read the whole thing.