[Yavanna228]

I agree with what Finwe said about Sammath Naur obviously not being at the top of Mount Doom. In RotK it says that the sides of the mountain were rugged, but not sheer, so maybe that helped somewhat in their ascent. I think that the climbing of the mountain was the truest test of the wills of Frodo and especially Sam, and when they came to the end of themselves, a path amazingly appeared, making the rest of the trek 'easier.'
I myself have only climbed one mountain, and that was done in health and fair spirits. I really admire Sam's efforts, and can only wonder if my mettle would have proved as strong.
Peace