Close your eyes.

Inhale slowly; then slowly exhale.

While exhaling, try to create heat in your breath. This should make a 'Haaaa' sound and will create friction in your throat, relaxing you and burning up those stray calories.

Concentrate on your breathing. This will help you to relax from pressure and will help to increase your concentration.

Visualize a balloon inflating and deflating as you breathe.
Stand up behind your chair and rest your arms on the back of the chair, with your eyes closed and head down.

Take a few seconds to find calm and focus amid a hectic workday.