It's partly because I get off on seeing them enjoy themselves - and it's so easy to make an animal happy! Endlessly rewarding.

The other reason is pride. It gives me such pleasure to have everyone who meets them exclaim over their shiny coats and their teeth and their bright eyes and their bounciness. It's worth it.

There's also the poo issue. You would not BELIEVE how much easier and less nasty it is to clean up after them on this diet. Tiny firm poo with almost no smell from all of them, because they're not swallowing a whole load of nasty crap their bodies can't use.

Oh, and there's the whole "I have no life" thing too, but I won't get into that...