Originally Posted by NutHug

If you want to punch left and then right start with a left turned chest and extended left pec. For the first punch change to a right turned chest, contract left pec, extend left hip and contract right hip. For the second punch contract your left elbow and extend the left pec to prevent uke from flying too far away. Change to a left turning chest and contract the right pec, contract your left hip and extend your right hip.

Legs are quite important when it comes to punching. Of course you need some fine adjustments to not fly away etc.