Boundaries. Establish them and defend them with every ounce of your being. If you don't, most employers will grind you in to the dirt and send you out to pasture when you eventually crack under the pressure. Better to establish healthy boundaries up front. Not only will you find yourself more frequently surrounded by people you like and share mutual respect with, you will be happier and land fewer "shit" jobs because employers looking for people to send to the meat grinder will see that they can't grind you down and you'll be filtered from the hiring pool before you ever have to suffer at their hands.