In his book The Confident Mind, Dr. Nate Zinsser writes about a journaling exercise called E-S-P: Effort-Success-Progress.
On your daily journal entries at the end of the day, add section for E-S-P and write down:
Effort: your moment of honest effort for the day Success: your moment of success, when you got something right. even small ones count. Progress: where you improved over previous attempts
If you had a particularly good day, you can of course add multiple moments for each.
According to Zinsser, this helps build a memory bank of positive memories of you performing your craft which in turn builds self-confidence.