I assume that the neighbors are not necessarily planning to enlist your services for personal training. This means that this could be an opportunity for you to display your skills, and I would present it as a menu that also has a package deal.
For example, the body fat and measurements alone could have one price, together with an aerobic test (such as the Rockport walk test) another, and yet another rate for a complete fitness assessment with pictures and all. I would charge my hourly rate for the whole thing, 50 % of that for the measurements with fitness test and 25% for the measurements alone. I would price it to make it attractive to get the entire assessment because this is a good starting point for a discussion on how to achieve improvements, and it may turn into business for you.