[reuben_tate]

From what I recall, I wasn't taught anything regarding mental health in either middle or high school, even though I had a Health class both in middle and high school.

Do any of the middle schools in your area have a Health class that students take? Maybe it might be worth talking to some of the Health teachers at those schools and discuss the idea of making room for mental health in the curriculum. Perhaps the teacher is bound by a strict set of things they are (and aren't) expected to teach the students though. In either case, it'd be interesting to get a better perspective on why mental health is a topic that is hardly covered.

One thing I'm curious about is your plan to get students to attend your thing. If it's after school, there might be some students that need to catch the bus, or whose parents want to pick them up immediately after school, or maybe the students need to immediately go home for whatever reason. There's also the issue of getting students interested in attending. Perhaps providing light refreshments might entice some students or perhaps having the health teacher provide extra credit to students that attend, idk. Or perhaps you could ask teachers if you could spend 5 minutes at the start of their class to tell students about your project and if you can make it seem like something that would be interesting/engaging for them, perhaps that might be enough to get some students to attend.

Talking about being interesting/engaging, it might help to plan some engaging activities for the students. Especially if they are middle school students...they probably don't want to just sit down and listen to a talking head for an hour :P