Rory McIlroy

What a difference a year has made for Rory McIlroy, who 12 months ago tarnished his reputation by quitting during the second round of the PGA Tour's Honda Classic.

McIlroy's head was a mess and his game was not much better at this time last year as he walked off the course citing a toothache, an excuse he later admitted was rather lame.

The Northern Irishman, who at the time was defending champion, was surprised by the widespread criticism he received for his withdrawal, but on the eve of this year's event he seemed genuinely contrite as he recalled the incident.

"My game wasn't where I wanted it to be and my mental state wasn't quite where it needed to be," a relaxed-looking McIlroy said at Palm Beach National on Wednesday.

"There were a few things occupying my thoughts that probably did not need to be and should not have been.

"It is difficult to deal with, especially when you haven't had to deal with it before. It was a bit of a shock to the system to me."

Without addressing specific details, McIlroy seemed to be alluding to multiple aspects of his life, both personal and business.

After ending 2012 as the world's top-ranked golfer, he endured a tumultuous 2013 as he struggled at times on the course, and off it as he ditched his management group in a dispute that is headed to court.

But he ended the year on a more upbeat note, winning the Australian Open in December before subsequently becoming engaged to tennis star Caroline Wozniacki.

"There were a lot of things I needed to change off the course to get my head right to be able to go on the course and just think about golf," said the 24-year-old McIlroy, who has already won two majors.

"That has been the biggest improvement from this time last year. You should never walk off the golf course, no matter how bad things are, but it was just one of those days. I just felt I couldn't cope with anything more, especially the way I was heading.

"I was going to shoot 90 (and) that was the last thing I needed. It wasn't my finest hour, at the end of the day. Everyone makes mistakes."