I'm not the most disciplined person out there. I don't practice my music or my writing on a daily basis and I feel bad about that.
When you are practicing a craft, it does go through scrutiny when the results are presented to others. After we hear feedback from other people, especially the negative kind, we ourselves tend to be judgmental and might not be able to withstand our own judgment of our work.
So. What to do?
Get back on the horse, so to speak. There's nothing else that can be done about that. Eventually, thicker skin will develop.