influence
Sometimes I catch myself doing something totally useless, when I can't get myself doing complex tasks (like studying). For a moment it doesn't seem right to stop altogether doing the task, on the other hand, continuing means suffering. So I seem to get lost in checking e-mails, watering the plants, playing a simple tune on my keyboard, etcetera. From an objective standpoint it seems much better to stop altogether and do something nice. This would mean much more relief than this kind of weird cognitive lingering between useless activities and the work that needs to be done. Also this kind of mental borderline-state seems to have a negative effect on my sense of individuality. The useless activities are not chosen, and the tasks I don't want to do are experienced as obligations.
If I stopped completely with the task and do something else (which I tend to do more often), I would have made a conscious choice which would stir my sense of individuality. Another possibility: If I continued doing the difficult task, that would mean some more suffering, but it would also mean taking it into my realm of influence. I would probably be able to solve the problem, which would mean one less, which means more freedom to do nice things (and the accompanying self-awareness).
Both choices would mean a greater alertness and increased sense of self. Only the 'non-choice', to do something useless, means a degradation of individuality. It's much like watching television; Which is not really relaxing and tends to rob people of their own minds.
So here is my advice: don't sit back and do nothing, if something for a moment doesn't work out and you feel stressed about it. Think! There are always some other useful things you can do. List them and try to do something which is a bit easier. Something you can do. Every solved problem means some more mental space. Focus fully on one problem at a time (all problems at the time isn't possible, but we can do one at a time). Try to get things into your realm of influence; Be fully responsible for all the things you do. Please don't live in a world where bad things just 'seem to happen'.
If you are tired, depressed, the tasks unbearably difficult and your energy levels at zero, take a moment and decide consciously to stop altogether. We have a word for such situations, it's called relaxing. It's not bad, it's necessary. Like I told you in the beginning, humans are not perfect. We need to develop ourselves in many ways. And one of those ways is knowing very precisely when you need to take a break.