First time riding a horse

So this is Sampson. He stands at 17hh and this is my boyfriends first riding lesson. After seeing me ride and knowing my horse obsession, he wanted to see what all the fuss was about. So after much deliberating we booked a lesson last week. Aside from apparently being 'extremely painful', he is hooked. He is also (depressingly) very good. It takes many people weeks to master the art of sitting and rising trot, he mastered it in less than 10 minutes.