Where are you Argo? He knows a thing or two about this.
I really want to see my nephews go far and having trained them I've learned manipulating them to want it themselves and for no other reason is foremost important, and don't forget he's just a grom. And as a dad you know how much he likes to push his boundaries, and his experience with those boundaries will make or break his fulfillment into a good rider.
And avoid ever having your kid think you have expectations of his riding.