Its doing the thing where it won't quote for me ("messages can't be found") on the multiquote.
@Exterous: Yeessss. True ATOTer
@Platypus: Good advice.
@GeekDrew: Yeah. Really, you should be alternating between sitting and standing (doing either one for excessively long times isn't great for your health). Many of the powered adjustable desks have the ability to set a timer where it will auto raise/lower the desk.
Another recommendation is to have a stool or something that you can maybe lean on as well to alleviate some pressure when you're standing.
They also make chairs that are for kneeling or even spinning around and sitting in backwards (has cutouts in the back so that your legs and arms aren't splayed out unnaturally; the back of the chair is where it'll support your back, shoulder blade/shoulders, and head when you're sitting, but then if you sit in it backwards you'd lean your chest against the back, your legs would go through and your upper arms could even rest on the shoulder/support area and then your chin on the top of the head area).