In addition to what Lisa already mentioned, I would start with your current clientele. You are already offering personal training, and the health coaching could be an extension of what you currently offer. They compliment each other very well.
I am also an ACE Certified Health Coach (and ACE Personal Trainer) and offer both kinds of packages to my clients.
Networking and exploring outside opportunities are great, but don’t forget about the clients you currently have and their referrals.