"I want to lock you up, boy. I like the power."
Perfectly valid and I'm sure honest answer, but that's not doing anything for me. I want a keyholder who says something so inspiring that it makes me want to take the afternoon off work and report for him to changeover to his lock immediately.
And so, I ended up describing why I'm into chastity in a more prefect way than I ever have before:
"Think of it like I'm a pup, and chastity is a trick I do. Then you can try to dangle something in front of me to get me to do my trick. Sure, you issue a command. Sometimes that's enough. But you can come up with a way to seal the deal if you put a little more into it. And then when it's all over and I've done my time, I get a 'Good pup!' to know you're pleased :)"