On Saturday afternoon, Sharon Hart, 48, looked out the window at Chicago's Rush University Medical Center, where she receives chemotherapy for acute myeloid leukemia, and smiled.
A message was written in the snow on the roof of the hospital parking lot:
"HI MOM. GOD BLESS U!"
Hart's 14-year-old son, William, had stomped out the "HI MOM" portion of the message. He later returned with his father and uncle and decided to extend the message to all patients with "GOD BLESS U!"
Photos of the snow writing quickly went viral on Twitter, Instagram and Facebook.
"It shows she raised an incredible young man and there is so much love in that family," said nurse Maura Hoyt.
[ Good News: 100-year-old BFFs share thoughts on selfies, twerking ]
"I still can’t believe this," hospital spokesperson Deb Song said. "People have called from Pittsburgh and Cleveland and said they saw it. People want to care about the good side. A story, even a small one, makes people feel good. We all want to feel good at the end of the day."
"We got such an overwhelming response from our doctors, nurses and staff who saw it and thought it was wonderful. The gesture was so simple, but so creative and nice," Song added.
"My son has never done anything like this before," Hart told the Chicago Tribune. "He is a very caring child and very loving ... He acted on instinct and from what was in his heart. I’m glad so many people got to see the message and that it touched so many. It shows how big God is."
Hart was diagnosed with leukaemia on February 3 and was immediately admitted as an inpatient.
"I wanted to send her the message because I thought it would brighten her spirits and help her get through this," said William, a high-school freshman. "I would love for her to be happy."
"This has been rough. I’ve been praying a lot and trying to not think about what’s going on so I can do good in school. I keep my hopes up and pray every night that my mommy gets well."
[ Good News: Donations pour in to help 'Wendy's Guy' get back on his feet ]
Hart is now known as "The Mom" at the hospital.
Because the hospital needed the roof for parking on Monday morning, snowplough drivers had to clear off the snow message. The hospital told ABC7 that the drivers were hesitant to do so.
The snow may be gone, but the sweet sentiment remains an encouragement for everyone at the hospital.
"No matter how cold it gets," nurse Angela Washek said, "there is always a message of warmth if we just open our eyes to see it.”