What would your limit be? How much pain could you handle for a stranger?

If you could heal any injury or illness, but in order to do so you had to take on and suffer said injury for one full day? Could you be blind for a day? Would you be willing to accept being paralyzed for a day? How about a week? Would you take on an advanced case of Alzheimer's if it would improve someone else's existence? What if you had to remember the fear of being lost even after your memory returned?