Everything has a limit. We should always prefer working hard, but we should never forget caring ourselves too. If you feel the below things happening to you then you need a break from the work; have some relaxation and the best way for that is going on a vacation.
When you are all stressed up, then even the minor issues seem to trouble you like a huge one. You cannot bear even the small things. Everything starts to irritate you a lot though the situation is not at all complex. If this happens to you; then you should understand that now is the time for a vacation.