BOSTON - Tim Shriver, Kennedy family scion and CEO of the Special Olympics, said Tuesday he is taking some time off to write a book about the athletes he says have changed his life.

Shriver said in an interview with The Associated Press that he hopes to tell the stories of the athletes in a way that will promote greater understanding of people with intellectual challenges.

"I came to this movement thinking I would help someone else, and here I am 50-plus years old and I think the athletes of this movement have taught me more about how to live this life than anyone ... There's a lot more here than a charity. There's a lot more than a cause," Shriver said.

The son of Eunice Kennedy Shriver and R. Sargent Shriver, Tim Shriver has headed the organization founded by his mother since 1996. Over the last decade, the organization has recruited more than three million new athletes from around the world.

Shriver said he will step away from the day-to-day activities of Special Olympics to focus on the book over the next few months, but will still be accessible to the staff. He plans to return to his post fulltime after the book is finished, perhaps as early as June.

Shriver has a publisher for the book - Farrar, Straus and Giroux - but no release date has been set yet.

He said he has been thinking about writing a book for years and decided that now was a good time.

"My goal is to awaken people to what I think many people don't realize, which is that the athletes of this movement - in their heroism, in their perseverance, in their courage, in their vulnerability - there are really important lessons for a time and an age when people are really looking and seeking ways to find more fulfillment, more purpose, more peace ... in their lives," he said.

Shriver has waged a public battle to end the use of the word "retard" and other disparaging words describing people with mental disabilities.

He received an apology from President Barack Obama after Obama told Jay Leno on the "Tonight Show" how awful his bowling scores were by saying, "It was like the Special Olympics or something."

Former White House Chief of Staff Rahm Emanuel also apologized for using the word "retarded" to describe liberal activists whose tactics on health care he questioned.

In 2008, Shriver called for a boycott of the film "Tropic Thunder" because of scenes featuring the liberal use of the word "retard."

"Our goal is not to humiliate people who use the word. It's not even to police them, but it is to educate them," Shriver said.

The first Special Olympics games were held in 1968. While Shriver is on leave, Special Olympics President and Chief Operating Officer J. Brady Lum will continue to manage the day-to-day operations. Stephen Carter, the lead director of the Special Olympics International Board of Directors, has agreed to have an increased role.