Speaking in a weak, husky voice from his home in Wiltshire, he said: "I was very confident - it is strange what the mind will do. He (the surgeon) was trying to prepare me for the worst, but even then I was confident.
"The next morning after surgery I was out of bed, walking around, moving everything. The worst thing was the voice."
Nicholson has been told not to ride for at least three months and is aiming towards starting the new season in March, believing he will be good enough to make the team for the Rio Olympics.
"It's my life and passion...living on the edge is all about why we do it," he said.
"I'm sure I'll be up to it (Rio) and my horses will be up to it. Whether Equestrian New Zealand are up to it...no I haven't (heard from them) and I don't really want to, to be honest. We are not on best terms and I can do without their input at the moment."
Nicholson's fall occurred while he was leading an event in Gloucestershire just over two weeks ago.