The life of an iguana pretty much consists of eating, basking, sleeping, and pooping.
My only suggestions would be to give him lots of different climbing areas, maybe multiple basking lights to give him some choices. Try feeding him some colorful fruit treats, always in moderation though. In the wild, iguanas are fairly social animals, congregating in groups of one male and several females. He may appreciate a stuffed animal that looks kinda like another iguana - as long as it isn't bigger than he is and intimidating to him.
She sits in her corner, singing herself to sleep.
Wrapped in all of the promises, that no one seems to keep.