They don't like thinking in medical school. They memorize - that's all they want you to do. You must not think.
I think the biggest challenge is to continue on the same path. I think it's easy to become complacent from the success you've had.
A man is as old as his arteries and his interests. If he permits his economic, religious, or social arteries to harden, or loses interest in whatever concerns mankind... he will need only six feet of earth.