The most difficult technique in martial arts is… walking through the front door of the dojo. Once you have done, that, the rest is possible.
It’s easy to use fatigue or minor aches and pains as an excuse. But if I had only taken classes when I felt fantastic, I would have taken about ten classes by now (over 40 years).
Oddly enough, I think I gained more by practicing under difficult circumstances than when I felt positive and energetic. Somehow, it just registers differently…
Consistency is the most powerful tool there is in training.