Only "Extra" was with Jennifer Lopez for a rare glimpse of another side of the star, as we visited with her and some very special guests.

"These are the kids from the Children's Hospital," Jennifer told us. "They came to visit me and hang out with me today."

And what a cool place to hang out: Jennifer's private trailer on the set of her new movie, "Monster-in-Law." For these kids -- all of whom are battling serious medical conditions -- it was a chance to live out a Hollywood fantasy: a day with Jennifer, on the set and away from their problems.

Jennifer surprised the kids with goodie bags of gifts, but the superstar was in for her own treat as they turned around and presented her with a present of their own.

The story of these children so touched "Extra's" special correspondent, Giselle Fernandez, that she made it into a documentary called "Our Story" but in this movie, stars like Jennifer, Will Smith and Leo Dicaprio are merely the supporting players, while a very special young man is the star.

His name was Dustin Meraz, an extraordinary 11-year-old who was both little boy and wise old sage wrapped up in one small body. And though he shared the Hollywood dream, he sadly didn't live to see these moments.

"Life is so short and they need to appreciate it a lot more, 'cause some people have it a lot worse than they do," says Dustin in Giselle's film.

Dustin dreamed of becoming an actor, and with the help of some caring stars, including Melissa Gilbert, Will Smith and Leo Dicaprio, he managed to get a membership in the Screen Actor's Guild before he died of a rare form of cancer.

"I have three children," says Will. "I can only imagine the pain and difficulties families have."

"He has such tremendous courage," Leo says of Dustin. "I don't think I'd have half of what this young man has."

Dustin was treated at the Children's Hospital in Los Angeles, as are all of the children who visited with Jennifer.

"I would contribute to whatever I can in helping them in whatever way I can that people care about them," Jennifer told us. No wonder she's regarded as an angel at the Children's Hospital.

Jennifer will be given a special award October 2nd at the Noche de Niños (Night of the child) Gala benefit for Children's Hospital Los Angeles. Marc Anthony will perform, as Jennifer is honored for her contributions.

"Extra" will have more exclusive moments with Jennifer, tomorrow, as she and Marc surprise 73 kids at the hospital.