Meh. Only the NSFW stuff I guess, but nothing that I wouldn’t tell someone if they really wanted to know.
But I stay off Facebook because I’m not interested in having an online presence or profile, so I guess in the sense of suddenly being thrust into that world at all, not related to the content I’ve posted just the literal online presence - that would bother me more, and the threat of violence or crime from being more visible like that.
Yoga in general and deadlifts are what I do. Back extension in both directions laying on your belly on a bench is good for strengthening it safely, start with small range of motion and extend it as you can.
Remember a few things - we spend more time bent forward than back, so make sure to strengthen the back in the arched direction as well. The whole body is connected so develop it in a balanced way. And move in every direction (intentionally). That last one is what yoga is so good for.