Justin Bieber has had his fair share of embarrassing mistakes in the past, but he has also racked up some goodwill from fans, particularly those children suffering from life-threatening illnesses who are being served by the Make-A-Wish Foundation, a non-profit organisation that grants the wishes of those children.

When he appeared recently on The Today Show with host Carson Daly, it was revealed that he had already granted the wishes of more than 250 children afflicted with such illnesses over the last six years. In fact, he has gone on record as the first celebrity to have granted the wishes of 200 ailing children.

To thank him, the kids he has helped decided to prepare a video for their favourite pop star. One of the kids in the short video was 10-year-old Monroe from California, who was battling leukaemia when she first met Bieber.

"When he walked in the door, she was speechless," Monroe's mother said.

The young girl is now in remission, and she proudly showed off the guitar that she had Justin sign when he visited her. "I walked around saying I was going to be his second wife," she said. "Thank you, Justin. You changed my life."

Another one of Bieber's fans was 15-year-old Alyssa from Florida, who is suffering from a congenital heart defect. She was one of the 20 lucky fans who got to spend some quality time with their favourite pop star in Los Angeles recently.

"He said he loved my hat and that I have a beautiful smile," Alyssa shyly said. And her father added, "It was like Santa Claus came to town."

To continue his streak of goodwill, Bieber will be granting the wishes of two more ailing children when he performs anew on the Today Show.