O.D.,
Honestly, I think it was all mental. I studied my gluts off studying for step I (about 5 months). I read a crap load of books, did a crap load of questions, and personally, I think I just choked when it came time to perform for step I. I think on any given day I could've scored 15 points higher (or lower for that matter) on step I. I went into step I mad stressed about the "perceived" importance of step I.
For step II, I went in with the attitude that all I had to do is PASS (since I took it so late). Studied for about a month. Started reading NMS medicine from cover to cover, but half way through the month, I realized it was impossible to finish before I took boards and abandoned that idea. Did all the questions in the NMS question book (about 1000 questions) and thought it was a great book. For the rest of the specialties I used an orange-ish review book that a lot of people used, but I can't remember the name right now. I thought it was good, but I didn't read a whole lot of it either.
So the short answer is that it was mostly mental for me.