If you’re doing a great job for your clients and they are seeing improvements in their fitness, they’re likely receiving compliments. When asked how they “look so good” they are probably referring their friends and colleagues to you anyway, but as an added incentive, why not offer a free session or two, or a free gift of some type.
You may find that you can offer a free gift (heart rate monitor?) at far less than your hourly rate for a free session, and yet it appears to your clients to be a better deal for them as they get to use it over and over again! A heart rate monitor for your client would be particularly useful in your cardio sessions with them.
This might be as easy as a free T-shirt with your company logo and contact details on it! That’s a double-whammy: more customers AND free advertising!
Don’t forget to put some clause in that the referred client must purchase X number of sessions with you before the bonus becomes active, otherwise you may lose out!
And finally, remember to promote this bonus on your website and mailing lists.