i guess even "older" guys like me can't get themselves away from the new trends.
I personally never believed Crossfit and the like will get you big muscles or anything like that, but if that is what it takes to get you to train, please do it!
Nothing is more important than your personal health, and if the group and timing mentality of Crossfit is what it takes, go ahead!
I dabble in bodyweight training myself sometimes and can only recommend training with gymnastic rings. But beware, it's hard. Really hard. I consider myself a well trained individual but damn my muscles aches are real, and i'm pretty sure any 8 year old with a bit of training would laugh at me.
So get out and get a cheap pair of gym rings. Hang them from a tree and start doing some pull ups!