Iguana enjoying the outdoors
I have had an iguana for 2 and a half years named Sammy. I usually take him outside once every three days so he can play in the plants i have around the back porch. I think this definately affects his behavior in a positive way because he's happier and much more energetic inside. His pigmentation is much more vibrant which i think has something to do with his general mood, and the fact that he gets natural sunlight often. Sammy the iguana is quite the lounger, though, and i suspect it has something to do with the fact that i feed him his greens quite frequently so he starts to get a big head lol.
About a year ago i had to take him to the vet because he had broken one of his fingers/talons whatever, and they fixed him quite easily, i was much impressed. Iguanas can have varying personalities and sometimes you will see a big difference if you get the chance to expose him to actual sunlight. You don't have to let him prance around in the back yard, you could just carry him around outside and see if you notice a difference in his iguana personality!