First lady Michelle ObamaMichelle LeVaughn Robinson ObamaObama on social media: You’ve got to ‘think before you tweet’ MSNBC trolls Trump with video montage of Obama saying ‘Merry Christmas’ Overnight Regulation: USDA delays healthy school lunch requirements | Senate panel advances controversial environmental pick | Drone industry pushes to ease rules | Dem commish joins energy regulator MORE on Saturday took her campaign to promote youth activity to the Arthur Ashe Kids' Day at the U.S. Open in New York. 

Obama was joined by tennis greats Serena Williams and Billie Jean King in announcing that the United States Tennis Association (USTA), partners of her Let's Move campaign, will build 5,000 more courts and train 15,000 more instructors. USTA will also work to attract another 300,000 young people to afterschool summer programs and donate hundred of thousands of dollars' worth of new equipment to kids.

"Because of the USTA, what they're doing, more kids like all of you are going to be out there learning to play tennis on kid-sized courts all across this country," Obama said.

Obama drew laughs when she said she’d be a “whole lot better” at tennis if she had learned it as a child.

"When you -- I was your age, I didn’t have tennis role models," Obama said. "I didn’t live in a community where there were any tennis courts. And, quite frankly, I don’t think I knew a single person when I was young who even knew how to play tennis."

"So this commitment is huge, because kids like you who are going to get involved in tennis, you guys are going to be way ahead of me," she said.

(Source: @FLOTUS/Twitter)

The first lady also said she has "forced" her daughters into playing tennis so they will be better players than she is.

“I’m not very good, so it’s easy," she added, to laughter.

"It's a good game to get your heart racing and pumping, no matter how old you are," she said, adding that players also benefit from hard effort, team work and discipline.

"I know your parents tell you that all the time, but I want to emphasize it -- if you want to be good at anything, you have to put the work in," she said. "You have to show up every day. You have to do your homework every single night without any exceptions. And you have to work hard for every test, for everything you do. That’s how you become successful. And you all can do it."