If I were in your shoes I'd be querying your friend's motivation.
Really? I have been in the friends shoes and I get where she is coming from, motivation is easier to come by if you can be convinced that yoy aren't going to damage a living being.
Not the same, but an insight into the working of a fat womans mind:
Last week DH and DS dusted off the wii fit and decided that we were going to all get back on the fitness trail. I refused to get on it.
A) My commitment to getting back to health and fitness started today, not last week.
B) Most important I know that the balance board with the wii has a weight limit, and I was convinced that I was going to get on and it was going to scream "GET OFF GET OFF, YOU ARE BREAKING ME"
This morning I eventually got brave and confronted those **** scales that have been collecting dust in the bathroom,
Well guess what, I'm actually 20 pounds lighter than I thought and well within the capabilities of the wii, and when it comes to it, to riding my new horse, I don't think he's going to break after all.
The fat womans internal dialogue is a very complicated thing.