Good idea, not always possible. For active people on two wheels or four, on snow or water, hiking, hunting or whatever — something or somebody can whack you. I have been lucky in around a quarter-million miles on a motorcycle and now closing in on 1000 miles on a bicycle (plus skiing, hiking, kayaking) — often alone — to not have been hurt along the way.
My friend John Chalmers was wearing a RoadID the other day when we rode together — an item about which I had thought before — and that spurred me to get one. Not expensive and it makes medical and contact info immediately available to first responders. I plan to wear mine 24/7 as soon as it comes in the mail. If you are active, think about it. Click the logo for more info.