posting at trot

Question
hello sir, why it is important to post while trotting. what happens if i don't post? can you please tell me how to post?

Answer
You don't have to post at a trot. Posting improves balance on the rider and encourages forward movement from the horse. If you don't post, the horse should slow to a jog and not a trot. Bend at the knees to propel your body up while trotting. Go up and down in the saddle. Count "out loud" "up...down". You will soon get in rhythm with the horse.