Well for one thing I don't do anything more than some relatively tame Class III scrambling-- you won't ever find me sprawled out like Spiderman on some vertical wall or anything like that ;-)  I'm not an actuary but I'd bet that there's a far greater healthcare risk to being inactive than to engaging in most physical activity with minor hazards and risks of injury.  My resting pulse rate goes up about 10 beats per minute over the course of the winter when I am mostly sedentary.