WASHINGTON -- When Curtis Granderson heard that the White House was requesting his presence for an important announcement, he knew that it was not the type of invitation that could be easily turned down.

That's how the Yankees outfielder found himself in a select audience in the State Dining Room on Tuesday afternoon, applauding as first lady Michelle Obama outlined a new nationwide campaign, "Let's Move," targeted at solving the challenge of childhood obesity within a generation.

Granderson represented Major League Baseball's commitment to help. Because of the 28-year-old's extensive history of involvement in community efforts, it should have been no surprise that Commissioner Bud Selig said he "can think of no better MLB representative" to enter the doors at 1600 Pennsylvania Avenue in support.

The Illinois native is the son of a physical education teacher, just one reason why influencing children to lead more active and healthy lifestyles is important to Granderson. Unfortunately, the childhood staples of recess, gym classes and playing ball until dark are on the decline.

"The things that I did were just second nature -- going outside and riding my bike," Granderson said in an interview with MLB.com. "I didn't realize they were paying dividends at the age of 5, 6, 7 years old. But now that I look back, I'm glad that I did it. I'm able to be in the physical shape that I am today because of those little things that I did. All of it was because of having fun and being a little kid."

Now he's hoping to help others do the same through this nationwide movement.

The anti-obesity campaign will set a national goal of solving the challenge within a generation for the first time. The program "will be designed to unite and inspire families to take real and sustained actions to eat better, be more active and make a commitment to embracing healthier lifestyles," MLB said in a statement.

In her address, Mrs. Obama outlined a comprehensive plan of action that aims to provide schools, families and communities with tools to help children be more active, eat better and be healthier. It is vital to start immediately, she said. Over the past three decades, childhood obesity rates in America have tripled, and nearly one in three American children is overweight or obese.

Mrs. Obama understands that it is not always easy to make the best choices. In the years before she had the White House staff at her disposal, long hours led to trips to the drive-thru window or calls to takeout restaurants. That might have continued if the family pediatrician in Chicago had not told her that he did not like the weight fluctuations he was seeing in the Obama daughters.

"That was a moment of truth for me," Mrs. Obama said. "It was a wakeup call that I was the one in charge, even if it didn't always feel that way. And today it's time for a moment of truth for our country. It's time we all had a wakeup call. It's time for us to be honest with ourselves about how we got here.

"Our kids didn't do this to themselves. Our kids don't decide what's served to them at school or whether there's time for gym class or recess. Our kids don't choose to make food products with tons of sugar and sodium in super-sized portions, and then to have those products marketed to them everywhere they turn.

"And no matter how much they beg for pizza, fries and candy, ultimately, they are not, and should not, be the ones calling the shots at dinnertime. We're in charge. We make these decisions. But that's actually the good news here. If we're the ones who make the decisions, then we can decide to solve this problem."

Earlier on Tuesday, President Obama signed a Presidential Memorandum creating the first Task Force on Child Obesity, which will conduct a review of every program relating to child nutrition and physical activity within the next 90 days. A Web site, LetsMove.org, was immediately launched in support.

Granderson was an interested observer at the formal White House media event, which featured several speakers, including former National Football League running back Tiki Barber.

"I think the big thing is relaying a message that you don't have to go outside and play a sport to be active," Granderson said. "Walking, running, riding a bike -- all of those things don't really require talent, as long as you have the physical ability to do it. You can do a lot of different things to get the heart rate up. Then, from a nutritional standpoint, part of it is just having another option, which is one of the things that the first lady is trying to allow for in schools."

Granderson, who spent his first six Major League seasons with the Tigers and was an All-Star for the first time in 2009, was making his second trip to the White House. He had been invited with several other big leaguers to enjoy dinner with President George W. Bush in December 2007, and he also had the opportunity to meet President Obama at last summer's All-Star Game in St. Louis.

Acquired by the Yankees in a three-team trade in December, Granderson established the not-for-profit Grand Kids Foundation in 2008, focusing on improving opportunities for inner-city youth in regard to education and baseball. Last year, he was named the Marvin Miller Man of the Year and was also a nominee for the Roberto Clemente Award.

As an MLB Ambassador, Granderson has visited Europe, South Africa and China to promote baseball.

"[He is] a role model and ambassador for baseball who has demonstrated a passion and dedication for all issues relating to enriching young people's lives," Selig said.

MLB also announced on Tuesday an expansion of its "Wanna Play?" initiative, a program dedicated to youth fitness that debuted last year with events in Cincinnati, Houston and Philadelphia. This year, it will be administered by Boys & Girls Clubs of America, the official charity of MLB, with a goal of reaching 175,000 members.

"Wanna Play?" encourages children 6 to 12 to increase their physical fitness by focusing on agility, coordination and balance while incorporating baseball and softball elements.

"I'd like to thank Major League Baseball and the Commissioner's Office for allowing me to come here and represent both sides in this joint effort with all the different sports and the government, to show the importance of getting kids back to being active and reducing the obesity issue that we have here in the U.S.," Granderson said.

"It's always exciting to get a chance to do something like this. It has a chance to affect so many different people, especially kids, which is what my Grand Kids Foundation is focused on -- educating kids and getting kids back playing baseball and being active."