As with everything, your first fitness profile should be free. If you're running measurement, nutrition advice, and a battery of tests, you will easily be with the client for an hour.
To make sure that the client stays committed, you can offer 1 fitness profile every month for a year at $50/month. For every client that agrees, that's an extra $600 per year!
Offering this service to just 10 clients can earn you an extra $6000 per year! Not bad huh?
Here's the best part, after a few months of doing things on their own and not seeing results, it will then be easier to offer them your personal training services..and THAT is how you get more clients.