Does turning 50 mean he now has an AARP card?
"Not that I know of!" Jackson said, laughing.
He said he still can do all his famous dance moves and "more."
"I feel very wise and sage, but at the same time very young," he said.
Reflecting back, Jackson said the happiest time in his life was probably when he was recording his hit solo albums "Thriller," released in 1982, and "Off the Wall," released in 1979. Those albums -- which were accompanied by a string of hit singles and videos and corresponded with the 1983 debut of his signature dance, the "moonwalk" -- propelled him to the height of his stardom.
"That meant very much to me and seemed to be received so beautifully by the public and the world," he said. "I enjoyed it very much."
Asked to pick a single song as his greatest achievement, Jackson went back to the same period.
"Oh boy, that's a hard one," he said, before singling out "We Are the World," "Billie Jean" and "Thriller."
But Jackson was not content to rest on his laurels, saying, "I am still looking forward to doing a lot of great things."
He hopes to release new music and tour, though he doesn't have dates set.
"I am writing all the time," he said. "I love composing and the whole thing. But I am also raising my children and enjoying it and teaching them to ride bicycles and how to read. I love it."
He said he hopes to "be myself" in his future work, but also that he is "inspired by many great artists," noting he wished he could have worked with Brown or Fred Astaire.
He sees his influence in some of today's artists, specifically mentioning Chris Brown.
He said he sacrificed his childhood with "a lot of hard work," and that he remembers "giving up your life for the medium."
But he'd do it all again.
"I think I would," he said. "It is very much worth it. I have always loved show business and have always enjoyed making people happy through that medium. I love the celebration of music and dance and art. I just love it."
Asked if he'd like his two sons and daughter to have the same sort of upbringing as him, he said he'd prefer to let them "enjoy their childhood as much as possible."
"I let them go to the arcade and go to the movies and do things," he said. "I want them to get to do the kind of things I didn't get to do. So, I fill them with a lot of enjoyment that way -- a lot of amusement. You know?
"I get pretty emotional when I see them having a wonderful time," he added, "when they are on a ride and they are screaming and they are happy. ... It makes me emotional, 'cause I see they are having a real good time."
Jackson said his kids "love music ... they are very much into the arts," but that, "I don't push them."
If he could go back and give himself some advice at age 9 or 10, the approximate age of his oldest children, he would advise himself, "if you are going to do it, commit yourself, know your craft and be really involved." He'd say to be strong and to have "rhinoceros skin" when it comes to dealing with the pressures of fame.
Perhaps Jackson learned to have a thick skin after enduring years of controversies.
Born Aug. 29, 1958, in gritty Gary, Ind., Jackson rose to fame as the youngest member of the brother act, The Jackson 5. The group released its first single on the Motown label in 1969, when Jackson was 11 years old, and enjoyed a string of hits in the early 1970s.
The group eventually became known as The Jacksons, and Jackson also had hits as a child solo artist and actor.
Jackson's adult musical career took off with "Off the Wall," and eventually, he became such a superstar that he adopted the moniker, "the king of pop."
But Jackson also developed a reputation for eccentricity. He often was seen wearing a surgical mask in public, and his appearance changed and his skin complexion seemed to grow lighter through the years.
He had a pair of brief marriages, including one to Elvis Presley's daughter, Lisa Marie Presley.
In 2002, Jackson drew criticism for dangling his youngest son, Prince Michael II, then a toddler, from a German hotel balcony as fans looked on. He later apologized.
In 1993, Jackson was accused of molesting a 13-year-old boy who visited his "Neverland" ranch, but settled the case out of court.
Jackson was criminally charged with child molestation in 2003, but was acquitted in 2005.
Is the Thriller Gone?
"Fifty should have been a turning point for him," said the man known only as Phoenix, who once served as a spokesman for the Jackson family and now fronts a tribute band called the Dancing Machine Revue. "The Big 5-0, so far, is not going quite as planned."
After the trial, the family relocated to Bahrain as Jackson fled the media he once courted. Jackson recently returned to the States and has been living in Vegas where he was photographed last month being pushed in a wheelchair while wearing a dreadlocked wig, sunglasses and a surgical mask.
The photo seems to contradict Jackson's own comments that he feels young and can still perform his famous dance moves.
When Jackson biographer Stacy Brown saw it, he thought, "Oh, he's looking for attention again," he said. "Then, I looked closely and said, 'Wow, he's really thin. Maybe there's a problem."
Brown, who was once close to the family and collaborated with Jackson's brother Jermaine and sister Rebbie on books, said Jackson's has a history of physical ailments. "He's battled lupus for years, especially when he's in a high-stress situation. And he's been under that for long time."
He has also battled addictions to pain medications and can put away a surprising amount of whiskey, said Brown, co-author of "Michael Jackson: the Man behind the Mask."
But Phoenix believes it's his emotional demons that are crippling him now.
"He's been under the weather for a while, but I believe it's more or less psychological," he said. "The world has always expected him to be energetic and lively. He has a lot to live up to."
"I think it goes back even further," said Brown. "He had a lot of pressure as a boy, then carrying the group, then being the focal point. It became too much. He let go of more important things in life, his faith. He became a self-worshipper. He let go of his family."
Phoenix, who is still in touch with Jackson's parents and brothers and spoke to Tito just a few weeks ago, said the family would like to celebrate Jackson's milestone birthday with him, but has been unable to reach him. "The family has been trying to get hold of him, it's very hard for them to get in touch with him."
Instead, family members, parents Joe and Katherine and older sister Rebbie, are expected to attend Phoenix's special birthday tribute concert in his hometown of Phoenix. His revue will play its usual mix of Jackson 5, the Jacksons and Jackson's solo hits.
For a while now, the brothers have wanted to reunite with Jackson for a tour. The last one they did together, the Victory Tour, was 24 years ago. A Jacksons tour, Phoenix said, would not only thrill fans but boost the brothers who have struggled financially without Jackson.
But Brown thinks even Jackson touring the way he used to appears to be out of the question. "I don't imagine he's physically capable," he said.
Brown is also doubtful about a new album. "He's been trying to complete an album for a long time," he said. "I think that's within his reach. But will it even really matter? He doesn't even have a record deal. That's what's really amazing. He's in a situation where has to prove himself all over again."
It's a very different situation from his fellow '80s pop icons Prince and Madonna, who also turned 50 earlier this summer.
While Prince and Madonna continue to make hit records, fill stadiums, appear at the Superbowl and on magazine covers, Jackson has become something of a recluse, releasing yet another album rehashing his greatest hits in celebration of his birthday.
"They were on a level playing field for a long time. Then Michael took such a bizarre turn to his life," said Jonathan Cohen, a senior editor at Billboard magazine. "Their careers could not have diverged more."
ABC News' Thea Trachtenberg contributed to this report.
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