I relate to a lot of what's been posted already about getting so focused and involved with a mix, in that it's very difficult to feel stoked about my mixes in the short term. However, for me it's normally just a matter of days until I can really hear it back and like it, not weeks. In the thick of the mixing stage...yeah, sometimes I start to feel like everything about it sucks and that I kind of want to just start everything over, but that's probably because I haven't taken a break or eaten a good meal and instead just pushed myself way too far! It also normally takes a few days for me to really dial in a mix. I'll get some things sounding good, but struggle with other things...then let it go for the day, come back the next day with fresh ears, and I can normally figure out what had been difficult the day before. After rethinking and revisiting things like this over a couple days, I always find the right balance of things and then start moving on to importing the same settings into other songs. Although...I often tweak the other songs somewhat, and then end up going back and "updating" what started out as the mix template, haha.