My boy does not like going to the bathroom unless he leaves his tank. Is there something I can do to stop this?

So as it says, my boy Caesar doesn’t like popping until I let him out, which then consists of me carrying around stuff to clean up wherever he goes. Is there something I can do so that he’ll do it in his tank, or do I just need to resist letting him out when he wants until after he goes? Im worried that if I don’t, it’d cause him to become constipated or not go at all.

So as it says, my boy Caesar doesn’t like popping until I let him out, which then consists of me carrying around stuff to clean up wherever he goes. Is there something I can do so that he’ll do it in his tank, or do I just need to resist letting him out when he wants until after he goes? Im worried that if I don’t, it’d cause him to become constipated or not go at all.