Upper-cuts are thrown with full force, as hard as you can throw them - there is no such thing as an easy upper-cut - a torking motion ensues on each side of your body with each upper-cut thrown - I like to verbalize this torking motion as "turning your chest to the sky" - there is also a slight explosion which may or may not take place with your legs upon throwing your upper-cut - although, many fighters choose to explode so much that their feet leave the ground when throwing them - be certain you can follow your upper-cut up with preferably a hook coming from the other hand.