By JAIME LUTZ

A 14-year-old boy, with some help from his dad, stomped out a love note in the snow that his mom could see from her hospital window and the note has cheered hundreds of patients and staff in the hospital.

Will Hart and his dad Tim wrote a gigantic message saying "HI MOM GOD BLESS U" on a parking garage rooftop visible from the top four to six floors of Chicago's Rush University Medical Center.

The note was meant for Sharon Hart, of Bolingbrook, Ill., who was hospitalized for acute leukemia last week. Before her son Will, 14,l visited her at Rush on Saturday, he had the idea to write "HI MOM" on top of the parking garage, which she could see from her window.

"It was just meant to make my mom and others feel good," said Sharon Hart's daughter Hannah, 18, who was at her job during that hospital visit.

Upon leaving the hospital that night, Will's father decided to add "GOD BLESS YOU ALL" to the rooftop note so other residents of the facility could be cheered by the message. But the father-son pair ran out of room, settling on "GOD BLESS U" instead.

A nurse on the overnight shift saw the family on top of the garage at around 1 a.m. on Sunday, but she assumed they were simply playing in the snow. It soon became clear that they were stomping out a message that, though it was intended just for one person, has touched hundreds - particularly the staff and patients of the hospital.

"It brought so many smiles to our doctors and nurses - and patients as well," said Deb Song, a spokeswoman for the hospital.

Hannah Hart discovered that the picture had gone viral when a coworker showed her the work of her brother during a break.

"We're going crazy," she said. "We could never imagine that something my brother did for my mom would grow to be this huge."

The Monday earlier, Hannah and her brother drove their mom to the hospital for what they thought was a stomach flu. But a standard blood test ended up showing a high white blood cell count - something that's a marker for leukemia. Sharon was diagnosed and admitted as an inpatient that day.

A message written in snow on the roof of the Rush University Medical Center's parking garage, Feb. 9. 2014. (Credit: Courtesy Rush University Medical Center)