For two years, Aaron Peterson strayed from competitive golf, figuring in time, he would return and pick up where he left off.

The process turned out to be more difficult than he anticipated.

Peterson, who played hockey at Eastern Michigan for two years after graduating from Huron High School in 2006, used a combination of trial and error, how-to swing guides and an occasional lesson to play his way back into golf shape.

He discovered he has trouble letting bad shots go and struggles to regain his mental edge - a lesson he learned again this week during a grueling run to the Michigan Amateur quarterfinals at Oakhurst Country Club in Clarkston.

Peterson appeared to be heading for a berth in Saturday's semifinals, taking a 1-up lead into the 18th hole of his quarterfinal match against Nicholas Carbary.

Peterson left his approach just short of the green and then flopped a shot into a bunker for a bogey while Carbary two-putted to force a playoff. One hole later, Peterson's tournament run was over.

"I was pretty deflated because I was so tired - 36 holes two days in a row is a lot of golf," Peterson said Saturday. "I just had a lot of mental fatigue. Mentally, (the tournament) is a grind. No matter how good of physical condition you're in, mentally, it's pretty difficult to maintain your focus the whole time."

Incoming Michigan freshman Joey Garber captured the tournament title Saturday, beating Eric Lilleboe 2 and 1.

As disappointing as Friday's finish was, it provided Peterson with another lesson to build on. After transferring from Eastern to Wayne State, Peterson has resumed his competitive golf career. Last season, he captured three tournament titles and was an all Great Lakes Intercollegiate Athletic Conference and PING all-region selection, finishing the year with a 74.8 average.

Peterson will play in a few Golf Association of Michigan events this summer while attempting to qualify for the U.S. Amateur championships later this year. Although he feels like his golf game is shaping up, getting back to where he was remains a work in progress.

"I thought it would be a little easier, but the combination of getting your swing and losing the muscle and getting flexible and getting your mind prepared to play in tournaments - it's a lot harder than you might think," Peterson said.

"I think I'm very close, but I'll pull a lot out of the (Michigan Amateur) experience to know that I need to develop a game and develop a swing I can completely trust under any condition and once I'm able do that, I'll be able to free up my mind a little bit."

Peterson has made the transition back to golf mainly on his own. He has gotten guidance from teachers and golf pros on a temporary basis. While his search for a full-time coach continues, he'll press forward, using experiences like last week's to build on.

Part of that process includes continuing to battle the mental challenges, often finding himself at times to be his own worst enemy.

"I put a lot of pressure on myself most of the time and then when I don't perform the way I want to, I sort of get frustrated with myself," he said. "But I'm getting closer to where I want to be and once I get my swing where it needs to be, I think everything will be a lot easier."

Jeff Arnold covers sports for AnnArbor.com and can be reached at (734) 623-2554 or by email at jeffarnold@annarbor.com. Follow him on Twitter @jeffreyparnold.