The first and most important challenge is posture while sitting. You've got to get that sqauared away. Speaking from painful experience, you cannot let asymmetries creep into your sitting posture, like e.g., leaning on your left elbow while working a mouse with the right hand, (with a wallet in your right rear pocket!) Learning forward with both elbows on the desk and your chin in your hands, terrible for thorasic mobility. Years of this will leave you with structural asymmetries that will eventually lead to injury. There's lots of good YouTube videos on sitting posture.

I could never get into standing at a desk. I do a lot of passive dead hangs throughout the day.