Oh god, I've given him an idea

Here's a conversation I recently had with my friend. Sometimes I can't help myself:

Me: Say, don't you have a spouse who tries every diet in the book to no avail?
Him: You know it...
Me: I heard about a new one that actually does make a difference.
Him: Go on...
Me: Just tell her she needs to go running; 5 miles in the morning and in the evening.
Him: Wow, that is all? And that really makes a difference?
Me: You bet. After a week of this she will already be 70 miles away and you can start looking for a new girlfriend without any hassle.