I used to have a pony (he died in 2010). Besides riding on his back, we'd also have him pull a cart occasionally. If we took the cart from the barn it was kept in (whether because we wanted to use the cart or because it was in the way) the pony would stand at the gate of his paddock and he'd stand there until he was either taken out - to be put before the cart - or the cart would go back into the barn, even if that took hours, he liked pulling the cart that much.