This is a good article with suggestions on how to deal with the stress of working at a desk all the time. I find that just taking a timeout for a few minutes, closing my eyes and taking some deep breathes really helps. AND, it makes your efforts more efficient, in case anyone were to complain about you taking a break.
Since I drink a lot of water, I often have to take bathroom breaks. As I am standing there relieving myself I take several deep breathes as my body relaxes. This is one way that I pace myself and kind of force myself to take these mental health breaks.
We work to survive, but if work is killing us then it is not worth doing. By bring mindfulness into our work we cut down the stress that it causes and can improve the quality of the experience of working. Being mindful of our attitude toward work, our co-workers and our work environment, reminding ourselves that a positive attitude improve the quality of our experience, we can greatly enhance our life experience that work is part of.
When you become aware that what you seek is quality of life, then taking a few minutes to enhance your work experience and create a healthier mind and body is worth it.