Children with low self-esteem have a difficult time dealing with problems, are overly self-critical, and can become passive, withdrawn, and depressed.
You need to develop a self-critical eye, so that you don’t fool yourself into thinking a piece of work you’ve done is good enough only to find that the editor who commissioned it doesn’t think it’s good enough.
The intensity of intellectual and manual application which Leonardo threw into the work is proved by the fact that he finished it within four years, in spite of all his other avocations and of those prolonged pauses of concentrated imaginative effort and intense self-critical brooding to which we have direct contemporary witness.