Mine has only just been diagnosed, but it is likely that i have had it for 15 years or more.
I fall over regularly, a combination of dyspraxia and a weak ankle and I have never broken a bone - except for the fractured vertibrae that were evident on the scan. That fall, one when I slipped on a wet grassy slope and landed heavily on my back was nearly 15 years ago, and apart from the excessive pain and discomfort for about three months after the event has never troubled me since.
Long before I had osteoporosis, I taught myself how to fall to minimise injury, but in the last 10 years I can remember exceptional falls, that did me no harm at all. I am always very quickly back on my feet and on my way again.