Damned if you stand, damned if you sit. So the problem seems to be a lack of general movement more than anything else... which raises the question:
How do I move around if my job involves being still?
Dr. Movassaghi recommends making sure you sit in short spurts. "Breaking up sitting can reset some of the damage that accumulates when sitting for extended time periods."
What does this look like? You could stand up when you're talking on the phone, or set an alarm every hour to briskly walk back and forth across the office. You can also choose the stairs over the elevator, or park your car farther away in the lot. Just. Move. Around.
When you do have to sit, make sure you have proper back support. The back of the chair should be angled at a slight recline, and press against the lumbar spine. Your computer monitor should be positioned at eye level, because when the neck tilts it causes pressure on your spine.