I think one of the difficult aspects of being human is having a single subjective experience at a time, and not being able to easily imagine that things would look different at another time, under a different mental state, even when you know it is the case with a ridiculously high degree of confidence.
My classic example is sleep. Whenever I have one night with very little sleep, I am usually totally ok the next day, but in the evening of the following day I get depressed and demotivated and everything seems to lose meaning. Before that happens, I don't see any reason to prepare for that in advance because I don't really believe it's going to happen, even though it has happened every single time in the past. When it does happen, everything seems pointless and I find it hard to believe that after getting a good night's sleep life will be awesome again.
A friend recently suggested an interesting view where she embraces this subjective variance. I never considered this view before. I like the idea, although I am not entirely sure what its application would be like. How does flowing with it work when you're simply depressed?
Another friend told me a while ago that context switches between intense work and intense socializing take a long time to recover from, and I felt that myself recently.
Intuitively I feel these problems are related, and I guess there must be a cool life hack to make dealing with both of them easily. As of now, I am still looking for that elusive hack, though.