The 27-year-old Ospreys centre made the shock decision to stand down from Test duty in the build-up to last season's Six Nations title defence and it was not long before suggestions of his discontent with head coach Mike Ruddock began to surface.
Parker distanced himself from the Ruddock saga again this week but explained how he felt compelled to turn in his stripes after starting to question his own commitment.
"I pulled on the shirt once and it crossed my mind that maybe I shouldn't be here and it should never be like that, especially when you are playing for Wales," he said.
"Every time you pull on the jersey you should be wanting to play 100%. There shouldn't be anything else on your mind.
"You are playing for the guys next to you and for the crowd and you are putting your body on the line.
"That is of major importance to me and there was one occasion when I was in two minds.
"It was only a little percentage but I thought I couldn't pull on the jersey because of it.
"There were a lot of major things going on at the time which were personal to me. I wasn't happy. I was all over the place.
It was really confusing for me."
Parker's decision came just months after he had helped Wales to their first victory over Australia in nearly two decades.
He spent his time out of the international spotlight "getting my head together" but indicated to new head coach Gareth Jenkins he was ready for a return at the start of this season.
"I hated watching it on television. The guys were always telling me I shouldn't have retired. A lot of things had gone on but I just got to the point where I just missed it so much," said Parker.
He was omitted from the initial autumn Test squad but Jenkins phoned him on Sunday, the day after Wales had drawn 29-29 with Australia, to offer a way back.
Competition is strong in the Wales squad. Parker was drafted in as a replacement for the injured Hal Luscombe and he replaces the rested Tom Shanklin at outside centre.
But he said: "This is a major step for me and I love the challenge. There are so many good players, especially in the centres. There are guys with amazing skills, a lot of experience and some young guys coming through."
Parker has enjoyed an "awesome" week back in the Wales camp and, given what happened earlier this year, he drew one telling comparison between Ruddock's regime and the support set-up Jenkins and assistant coach Nigel Davies have built since they took charge in the summer.
"Gareth has got a very tight ship. It is very structured, like before, but the coaches now are very personal. Gareth is very good with the players and they all respect him," said Parker.
"It is the same with Nigel. Everyone is very personal and they try to help you both on the pitch but also if you have problems off the pitch.
"For a player that is important. You can't be thinking about your life off the field when you are playing otherwise you are not doing your job properly.
"Life has gone full circle for me and everything is going the right way for me now. I am completely happy off the field.
"I'm really excited about coming back. With the World Cup just around the corner I'm ready to fall back in love with international rugby all over again.
"I'll be even more determined this time around to show my appreciation to the coaches for coming to get me and to the fans who have stuck by me."