Phelps confirmed his intention to make one last run at the Olympics on Wednesday.
"You guys heard it here first," he told reporters at Skyline Aquatic Center, where he will be competing in his first meet since serving a six-month suspension by USA Swimming after a second drunken driving arrest last fall. "I am looking forward to next year. I don't think it's too hard to really realize why I came back."
But Phelps said he won't be swimming at the world meet in Russia in August as part of the punishment set forth by the sport's U.S. governing body. He had already qualified in three events before being banned from the last major international meet before the Rio de Janeiro Olympics.
"I really enjoy being on those trips," he said. "That's why it is painful to think that I won't have the chance to compete at worlds."
However, FINA executive director Cornel Marculescu told the Associated Press on Thursday that it would be "no problem for us" to offer Phelps an extra place at worlds with a special invitation, but that it has not been discussed with the U.S. team.
"We may give him another status because he's the greatest athlete [in] history," Marculescu said. "We can do whatever. He is the No. 1. He doesn't need the accreditations."
Phelps was adamant Wednesday that he did not want to displace a swimmer who earned selection in his absence.
"By no means do I want this to be a distraction from the team," he said. "No way would I ever want to displace a member of that team."
Instead, he plans to compete at U.S. summer nationals in San Antonio during the same time as worlds.
Phelps is back in Arizona, where he attended 45 days of inpatient alcohol rehabilitation after being arrested on DUI charges in his hometown of Baltimore last September. He offered no specifics about his treatment, which he continued in Maryland. He is also attending Alcoholics Anonymous, he said.
"The last couple of months have probably been the hardest I've ever had to go through in my entire life," he said. "I take full responsibility for all of my actions. I've hurt a lot of people and it's been terrible."
The 29-year-old swimmer was sentenced to 18 months of probation. He said he's done more growing up in recent months than he has in his entire life.
"I have been able to come out on a better end, have a clear head," he said. "I don't think I've ever been like this once in my life."
Phelps' longtime coach, Bob Bowman, acknowledged his star swimmer's second arrest for drunken driving made it "pretty hard to convince me that anything was going to lead us back to something that we'd be proud of."
Phelps called Bowman a few times from rehab, which the coach described as "really weird" because he typically never heard from Phelps away from the pool. Bowman visited Phelps during treatment, still skeptical that the swimmer was there for any reason other than he had to be. But Bowman left thinking differently.
"I just had no doubt that he had changed in a way that was really meaningful," Bowman said. "He was completely different and it's been that way every day since he's been back."
Phelps pleaded guilty after his first drunken driving arrest in 2004. Five years later, a photo was published of him using a marijuana pipe at a party, which drew a three-month suspension and caused some sponsors to drop him.
Phelps knows not everyone will believe he's contrite and has changed.
"If somebody doesn't believe the words that are coming out of my mouth that's their choice," he said. "I, of course, would like to show everybody in the world that I am in a different place and I am much better than I ever have been. I understand that's going to take a lot of time. This week will be the first week that I can start that."
Phelps will be competing in Mesa for the first time since the Pan Pacific Championships last August. The Arizona meet was where Phelps made his comeback a year ago after an extended retirement following the 2012 Olympics.
He isn't sure what to expect, having only recently returned to the kind of hard training he did before the 2008 Beijing Games, where he won a record eight gold medals. Phelps is falling back on the mentality he used for much of his career.
"I would just get up and swim as hard as I could and leave it in the water," he said. "That's what I'm going to do here. I know I'm more prepared now than I was at this time last year."
His first event is the 100-meter butterfly Thursday, when he'll compete against longtime rival Ryan Lochte. Phelps was wearing a shirt from his new "MP" brand that launched Wednesday. He'll be wearing his new Xpresso suit for the first time after he and Bowman collaborated on its manufacture with Aqua Sphere.
Phelps is surrounding himself with familiar faces this week, including his fiance, Nicole Johnson, and family members.
"I'm a lot happier and in a lot better state and in a lot better physical shape than I really have been in a long time," he said.
Phelps sets sights on Rio
Olympian Michael Phelps discusses his return to competitive swimming and his intent to participate in the 2016 Summer Olympics.