You don't have to play football to break a bone. Getting off the couch and walking to the fridge could do it if your bones are brittle. (so, keep a small fridge near the couch.) ;o)
Old women often don't fall and "break a hip"....what happens is a bone BREAKS, causing them to fall....and yes, ACTIVITY does help.
That's why I have a wife. To fetch things for me. (Gawd, I hope she doesn't read this.)