"stay rational."
Welcome! Have your favourite tea with an article...
meditation board..."I never did anything worth doing by accident, nor did any of my inventions come by accident; they came by work." (Plato)
Time to take a break! Sit back or stand up for 5 minutes, maybe have something healthy to eat or drink. Take a step back from life and just relax from everything around you. There is very little in life that is worth your right mind; the more one lives the more this is realized. The more one lives, the more it is realized the benefit of cooling the passions, thinking dispassionately.
Reading mathematics or any cognitively demanding text can be difficult, even discouraging sometimes; the writer knows from experience. Great ideas, while written in little time, took days even months for the authors to come up with. Give yourself the same standard and come back to previous mental blocks with a fresh mind. In the end, when you think you can't understand something remember that there is nothing one person ever did that can't be done by someone else. There is no 'self' and hence nothing unique to what anyone does. This means chains of reasoning are universal among everyone given enough time. Keep going!