RIYADH, Saudi Arabia — Mixing subjects linked to sports, society and business, Olympic champions Michael Phelps and Carl Lewis appeared at an economic gathering Tuesday to promote sports in Saudi Arabia.

From questions about Phelps' struggles with attention deficit disorder to Lewis' take on the racial makeup of most of the world's top sprinters, the pair also spoke about their own achievements.

"I'm never satisfied," Phelps said of his desire to be the best swimmer in the world. "I always want to do better than I did last time."

When it comes to the Olympics, Phelps proved that in Beijing. Four years after winning six gold and two bronze medals at the 2004 Athens Games, the American swept all eight of his events at the Watercube to become the most successful Olympian of all time.

That feat was certainly not lost of Lewis, a former world record-holder in the 100 meters who collected 10 Olympic medals in his career, including nine gold.

"Before this year, I used to always brag about winning nine gold medals. You taught me about changing rules," Lewis said as he looked over at Phelps. "So now I won the most medals of the last century."

Phelps and Lewis were in the Saudi capital for the Global Competitiveness Forum, appearing alongside Norwegian speedskating great Johann Olav Koss and Special Olympics chairman Timothy Shriver.

Despite the wide range of topics, the one item barely discussed was how gender gaps in sports can be closed.

The subject is highly sensitive in Saudi Arabia because female participation in sports is highly restricted. The kingdom does not allow female athletes to participate in the Olympics, and female sport leagues and physical education classes in government girls' schools are banned. Female guests cannot even use the gym in most Saudi hotels.

"It's too complicated to talk about in 30 seconds," Lewis told The Associated Press.

Besides the discussion on the panel, Phelps and Lewis also took questions from fans. Khaled al-Sharif, a young Saudi boy who also has attention deficit disorder, asked Phelps what it was like growing up with ADHD and wondered whether it helped him become an Olympic champion.

Phelps told him that he was motivated to excel because he had teachers who said he would never be successful at anything.

"I said to myself, 'I'm going to find something that I can really focus on and show them that if you put your mind to something you really can do it,'" Phelps told al-Sharif. "Swimming ... allowed me to focus."

Phelps, who said he planned to meet with some Saudi swimmers and do a few laps in the hotel swimming pool later Tuesday, has already said he wants to compete again at the 2012 London Olympics. However, he also noted that he would probably swim in fewer events.

But that doesn't mean he doesn't have more to prove.

"I've got four more years," Phelps said after being asked if he just wanted to take it easy in the wake of his achievements in Beijing. "There are still some goals there driving me right now, but in four years, I will be hanging the suit up and trying to live the easiest life I can live."