Ardha Chandrasana

The half-moon posture

This is an upright balance posture which requires a lot of strength and mental focus. Balance postures help you to achieve lightness of movement, strength, agility, muscle tone, control of your body, coordination and concentration.
This posture is not recommended during periods or pregnancy. The half-moon strengthens the legs, arms and shoulders, works the spine and back, opens up the chest and helps breathing. It's a difficult stretch and it will increase your heartbeat.  

How to do it.
The moon. Start in the triangle position (feet wide apart, right leg turned 90° outwards, left leg turned 15° inwards, arms raised to the height of your shoulders, palms down. Flex your right knee and place the fingertips of your right hand on the floor. Get your right leg in position by lifting your left leg until it's parallel with the floor. Hold steady on the right leg, turn your left shoulder back, lift your left arm and look above your shoulder. 
To release yourself from this position, lower your left leg to the floor, put your right leg back and go into the position you started in. 

Variation (see photo). When you're in the half-moon position, bend your right leg and point your toes towards the ceiling. Fold your right arm and grab hold of the end of your right foot. Lift your knee a little to open up your chest upwards.
At first you'll find it difficult to stay in this position, it will be uncomfortable and you'll find it hard to look upwards. 
Try focusing on a point on the ceiling and don't move your eyes. Hold for 5 breaths, and repeat on the other side.