The best thing you can do to counteract the harms of sitting is just to get up and move every 30 minutes or so, according to a study in the Annals of Internal Medicine. You should still try to meet exercise guidelines, but you can keep your desk job — just remember to take breaks.
In 2015, a group of researchers published a consensus statement in the British Journal of Sports Medicine, saying that people should spend two hours out of their seat each day during the workday.
Walk around, take meetings on the move, take calls while you take a stroll. Try a sit-stand desk so you can alternate between sitting and standing. And remember that taking these breaks will make you healthier and more productive in the long run.