TIME - Other than learned skills, the primary commodity an employer buys, is your time, which is finite and a different quantity for each individual. Stress shortens life. It's ok to work hard at something and preferably something that brings you satisfaction, but it is equally important that you balance time spent at work with personal pursuits which should take up a large percentage of your day/week and allow the feeling of abundance and joy. Essentially, this time spent in personal ways provides the moments of pause necessary to truly appreciate that paycheck because you are feeling, directly, the reward. When you spend too much of your day/week on work rather than personal things, you are just a hamster in a wheel. And this would be sucky job satisfaction.
We all want job satisfaction because we want high quality output. We also want balanced and friendly people. I have seen some strange come from folks who routinely skip their PTO and overwork too much. When you are too tired, things take longer and flat are not done at the best level because you are no longer at your best.
WHEN YOU TAKE CARE OF YOU, YOU ARE ALSO TAKING CARE OF THE COMPANY. Taking care of you works in three ways. Firstly, you want quality of life and quantity. Ultimately, you want to live a long and healthy happy life. When you are healthy, due to more free time and less stress, you gain more productive to society years. Next, your company directly benefits from you taking the very best care of you. There is less spent on sickness and shoring up when you are absent from work. There are also fewer mistakes. Lastly, if you do get the ax, you are not a spent shell of a person out there hoofing the pavement looking like leftovers.