Previous Position

Reverse punch (Gyaku Zuki) in Front Stance (Zenkutsu Dachi)

Punch from your hip with your Left fist.  The punch should finish directly in line with the centre of your chest towards the 1.30 clock position.  

Pull your Right fist quickly back to your hip
Push your Left hip forward and your Right hip back to give more reach to the punch
Make sure your Right knee is over your Right toes
Do not lean forward
Breathe out completely and tense all your body muscles for a brief moment on the completion of the move