2 of the best from my high school days are still around, though I barely even lurk anymore.

https://forum.bodybuilding.com

https://www.bluelight.org/community/forums/

Misc was a magical place back in the day.

I'll never forget there was a kid that weighed something akin to 600 pounds who posted as a troll but everyone started giving him helpful advice and encouragement. He lost hundreds of pounds and I believe even entered a bodybuilding show.