Squeeze and grip your glutes. Do it sitting or standing. Stand with hands on a table or desk for desk push (core). Push the surface toward the ground. You should feel your core engage.
Oblique twists develop abdominal muscles on both sides. Strong obliques burn fat, support the back, and improve posture.
Pushups and planks train your core and upper body simultaneously. Consider completing a plank or two pushups when you stand up from your desk.
You can build your quadriceps (thighs), your body's largest muscle group, at your desk.
Calf muscles assist you run, walk, jump, and balance. They gain from calf lifts. Sit and do calf lifts. Add weight to your lap or do calf lifts behind your chair as you get stronger.
Weak glutes and tight hip flexors can cause dead butt syndrome, numbness and soreness in the buttocks, hips, and lower back from sitting too much.