FB Strong Day 2 #workoutcomplete #2019complete + Pullover question

Whew! My arms are about to fall off! I've done this superset workout + burnout with Daniel, and it never gets easier!! I am toast by the third set, especially for triceps extension. I am feeling good, though, and less guilty about going out for burgers on my kind boss' dime today.

Quick question - does anyone know how to do a pullover correctly? I understand that I need to keep my lower back planted on the ground and only lift the weight to above my shoulder. I try to do this but for some reason, I find it to be ineffective, as in my shoulders rather than my lats feel sore. What am I doing wrong, or is there an alternate method of working the same muscle? Thank you!!

Wishing you all the best NYE, wherever you are in this world.