Psychological and Spiritual are one thing, but poisonings are the hardest things to overcome due to the disabling affect that you have to work out over time. Walking 5 miles and carrying a load is one thing, but when you have cyanide poisoning it is like you were soaked in ice cold water then someone hit you with an aluminum bat. You have to struggle to not vomit, have a stroke, and just die on the spot, as your arm, neck, and left side of your head freezes, including the breath in your chest. A very disgusting feeling.