Saved myself from being concussed twice in college (falling on ice, low speed collision with a car).
Now I do tai chi and I've had at least three bad stumbles on steps or sinkholes that would have put me in a leg cast ten years ago and I was just fine because I took all the weight off of the misplaced foot and sank to the ground.
Several of these remind me of similar injuries friends and family have experienced and I'm very glad I didn't have to go through the same thing.
If I were in charge of PE, every kid aged 10 and over would be a tumbling master. Then I would start teaching them sports.