Difficulty - Moderate
Muscle Groups Addressed - Glutes, Quadriceps, Hamstrings
A favorite of mine, wall squats have so many great benefits, not to mention they work all the primary muscle groups involved in proper sitting posture. It's bad enough us desk jockies have to sit in front of a screen most of the day... compounding that is the fact that most of us don't even sit properly.
Over time, poor seated posture can lead to spinal misalignment, joint degeneration, weak shoulders, and even a potbelly. As you slouch forward, your shoulders and back round in, loosening your pectorals and pushing your belly out. Wall squats done correctly will firm your core, build a strong lower back, and work your hips to help give you a balanced seated posture.
These work the same in the office as they do in the gym. Simply find a wall and lean back against it, standing up. Bending at the knees, slowly lower yourself down into a right angle seated position. Squating down too far and not having your feet out far enough will be unneeded pressure on your knees... envision sitting on a box. Stay "seated" for 10 seconds, then straighten your knees and come up, still leaning against the wall. Give yourself a 5 second break, then come back down and hold the squat for 10 seconds.
To really kick it up in the hamstrings and lower back, try raising one leg at a time, and holding.