Prolonged periods of sitting can induce glute inhibition. That makes logical sense. The whole point of a chair is to support your muscles so they don't have to do much work. What can be a result though? Dead butt syndrome. The muscles that run your entire backside from top to bottom essentially turn off when sitting (and form the shape of your chair). And your front side collapses and becomes weak and tight.
To reverse the affects of sitting, get your glutes firing. You'll protect your lumbar spine and decrease load on your knees. You'll move with greater stability and confidence. You stand tall with your shoulders back. So here're a few straight forward exercises to bring your butt back to life:
Hip bridges - Lie on the floor, Slide your feet towards your bum . Driving with your heels and squeezing your bum, raise your pelvis towards the ceiling. Try five to ten reps. Take a rest, and then do a few more until your bum and hamstrings are feeling nicely energized.
Supermans/womans - Lie on your stomach. Simultaneously, raise your arms and legs. Don't bend your elbows or knees. When your arms and legs are maximally raised, bend your elbows and drive them towards your bum - you should feel pressure between your shoulder blades. That wonderful area supports good and proper posture. Try three to five reps and repeat until you're flying.