I think there can be a tendency to get self critical and I also think that someone struggling and trying very hard can experience a time period where there might be a feeling of gaining on the challenge and then something can trigger bringing on once again a period of self doubt, even at times self loathing for not progressing as was desired.

Patience with self is extremely important. If I am finding I am getting triggered I have learned to step back from whatever it is and give myself time to recover myself.