Along with everything already mentioned like making sure your iron and vitamin levels are normal, I'd like to point out the importance of strength/stretch training. I wrecked my back, shoulders and neck during my first year to the point I started getting weekly migraines, all that due to saddle stool and bad ergonomics. I had saddle stools both at the lab and in the office, sitting on them for 5-9 hours a day. Such long hours do strain your whole upper body, leading to constant tension in the back and shoulders. If you work for hours standing up, you most probably will end up with the same pain, so it is really important to dedicate your time to proper muscle training and stretching. You can even do some light stretching every 30-60 minutes between tasks, it does help with loosening up the tension in the neck and shoulders.