Overly active monitor lizard?

[dinosaurdammit]

My goulds/argus cross is super hyper. A bottomless pit. How do I know when enough food is enough. He eats SO much but I dont want to deny him food for fear he wouldnt get enough. Also, he is super hyper active, he walks and tripods to look around and just is always on the move. I feel like this might be normal but I just wanted to be sure. If I had to guess that little guy walks about 6 miles a day, if you were to be able to measure it. Also, he love stairs- like LOVES. Goes up and down for fun I suppose. Lizard jazzersize isnt an issue apparently as he must be the Richard Simmons of the reptile world. I dont think I will have to be worried about an overweight monitor but I dont want to over feed and make him sick :/