Leave everything behind and take a day off. It’s a sound advice from no other than a Nobel Laureate, Paul Nurse.
Don’t work too hard because you would end up in the same direction. Similar to what successful authors say, write and write and then leave everything behind. After a couple of days, revisit your work and you would see it in a different perspective.
It may seem counterintuitive but it does work. Perhaps not for everyone, but it is definitely worth giving a shot, don’t you agree?