Sitting all day behind your work desk could be really difficult. Prolonged sitting may cause abnormal blood circulation throughout your body. This may result to pain in the back, in the neck, and in other parts of the body. To avoid this, we have to stand up once in a while to allow blood to circulate freely. 
Being comfortable with your workplace is essential, too, especially with your chair, as this is the place where you will be staying for the next few hours. It would be nicer if your seat would be soft but, if not, a chair with a good structure would be a must. I think it goes without saying because I am sure you know what it feels like to sit on a poorly constructed chair (very hard; limited seating capacity). When this happens, it's difficult for us to think and, thus, it's difficult to work properly.
It's also worth it to have some form of entertainment or diversion when. Listen to some music via your geadset, have a break for a while and play some game, perhaps, as long as you do not take much time since the essence of doing these activities is to just have a break, anyway.
Whatever you work on in front of your desk--may it be an undergraduate thesis, a report to be delivered in front of the board of directors, a short story that you have been wanting to send to some literary contest, or you simply just want to sit in front of desk--always be comfortable and happy with your condition. Never do something just for the sake of doing it or doing it even though you do not feel well. Let us be productive. We won't be if we are not happy.
All UPSable
