I recently spoke about this on a podcast. When asked how long you should stay at something you do not enjoy, I said it depends on how much pain you are willing to endure. It shouldn't come to that, but too often it does. Part of life balance is enjoying whatever you are doing. If you do not enjoy doing something, you have the power to stop it. If not, then you threshold of pain is high. Otherwise move on to something that fulfills you. Life is way too short