Sympathy and good will are vital supports in times of difficulty, and this was very much the case when one woman initiated a campaign to help lift the spirits of her friend's son who is fighting against lymphoblastic leukemia at the Phoenix Children's Hospital.

Roberta Lucero-Koron posted the "Photo Doggies for Anthony" campaign on Facebook last month, encouraging people to post happy pictures of dogs to cheer up 17-year old Anthony Lyons, who was diagnosed in July and faces years of difficult chemotherapy treatment. 

"Hi all, my friend Kristen Lyons has her son Anthony at Phoenix Children's Hospital. Some days he gets doggy visits (in pet therapy sessions) and some he does not. They make him smile. I thought if I create this event, you can post picture of your dog to help make him smile. His mom shows them to him and he smiles," said Lucero-Koron in her post.

Anthony told KSAZ news channel that doggy visits to the hospital always make him happy because the dogs are always happy. He went as far as to say that the dogs are the only thing that makes him feel better.

"It really helps, the pet therapy. Like I can be in here having a really bad day and then one of the dogs will show up and it will be the highlight of the day," Anthony told KSAZ.

This simple gesture of Lucero-Koron went viral as 620,000 Facebook users posted their photos and words of encouragement to cheer up Anthony.

"It started off just us thinking it was going to be some customers at a place I used to work, and it got to be 300, and we were so excited," Anthony's mother, Kristen Lyons, to the NBC News.

"Then out of nowhere, it's almost a million, and we cannot believe it. We're so excited. We're always looking at it trying to keep up with it every day," she added.

The huge number of photographs posted to the page show dogs making all kinds of silly and funny faces, some in costumes and others just hanging around. Most of them have messages of comfort and well-wishes for Anthony.

Lauretta Camden posted a picture of a black Labrador with a message, "This is Jake, my Lab/Rottie mix, wishing you a speedy recovery from Virginia." ; Mallory Halpin posted a picture of Maddie, a 6-year old Shih Tzu with a message, "Hope she brings a smile to your face like she does mine!" ; Debbie Stratton Davis posted a picture of her dog saying, "Hi Anthony! My dogs helped me through cancer and I know all your friends can help you kick cancer's butt too! Here's Rio from Denver, after a bath."

"They all make me laugh, all make me smile as I scroll through it. It's not a single one that doesn't make me smile," Anthony said.

"You always see the bad stories about abuse. [But] So many people are reaching out, and it just really shows a lot, and it means a lot to us. [This] really restored my faith in humanity big time," said Kristen.