Duration: as little as two minutes – longer if time allows
If a private space is available, practice this technique lying down. Otherwise, just make yourself as comfortable as possible.
Close your eyes. Take a big, deep breath. You are going to be holding your breath, so breathe in as deeply as possible.
Holding the breath inside you, start clenching or tensing your limbs one at a time. Start with your feet and ankles, then move upwards to your calves, your knees,
then tense your bottom. As you move upwards, do not loosen the previously clenched part of the body.
Now move up to your waist, then to your stomach. Tense your stomach muscles as tightly as possible. Automatically, your groin muscles will also get tensed.
Next, move upwards to your chest and back. Tense all the vertebrae along your back. Tense your arms and hands, starting from your fingers and moving up to your biceps. Tense your shoulder blades, your neck and throat muscles. Especially hold the tension in your neck muscles.
Move to your face. Your face has more muscles than you are aware of. Tense the muscles in your mouth, nostrils, eyes, eyebrows, forehead and cheeks. Squeeze
your eyelids shut. Clench your teeth. Screw your whole face into a tight ball. Remember not to relax the rest of your body during this time.
Stay in this state of tension for as long as you can. When you can’t hold your breath any more, expel it in one big gush, simultaneously relaxing your body utterly.
Stay in this state of physical and mental relaxation for a minute. This technique relaxes both the body and mind and refreshes you in just two minutes. If time allows, repeat the process three times.
source: Living Enlightenment