Try poking his nose out and stretch his neck out and also stretch it up and downward to the ground also point his nose upwards
Love carrot stretches! I do both sides and chest to different heights, and use the chest stretch as a precursor to learning to bow/lie down. Also stretch the legs to the front and back, and I like pelvic tilts and back stretches but am struggling to teach my horse to do them....
You can do bow we're you put the carrot in between his front legs on the ground and he goes do get it
You can also do side down, side towards the flanks and also in front that they point their nose very far forward, and make a long line with the back.
Leg stretches are good too