Thank you guys, all really good information. I will have to digest it! I have the basic structure of the site laid out. It is geared toward fostering exchange and encouraging interaction between members with each subgroup (with the exception of "medical conditions in the field") having it's own introduction and event forum, and a separate discussion forum. There are also chat rooms set up for each subgroup, including each medical condition listed in the "medical conditions in the field." I think I have a great layout established and it will be a matter of fine tuning for the rest of the week.
As far as marketing personas go, I have a total of six profile-types of users around which the site is built. Yes, you read that correctly, six. Each one has a unique set of goals and needs relative to health in the outdoor space, and as such has its own subgroup. To foster communication and exchange across groups, there is a collective "bragging board" where regardless of health challenge or preferred activity, members can post to share major accomplishments, milestones, harvests, and significant events in their outdoor life.
I look forward to really diving into these ideas and coming up with a game plan! Thank you all again!