I hear this term thrown around a lot, push myself beyond my limit and so forth. I'm not sure I understand what that means or if it's even wise and healthy. Beyond someones limits? For an athlete/backpacker woudn't you be dead if you go beyond. I've pushed myself farther than I wanted to lots of times but never "beyond" my limits. Perhaps that's why we here of many marathon runners (many may be overstating) falling over dead with a heart attack. Someone enlighten me so I understand. Is it safe/healthy to really push ourselves on a regular basis? Is it/can it be dangerous?