Next time you see a green balloon at Disneyland, I hope you think of a little boy who has a difficult time in big crowds.

He has trouble keeping his hands to himself. He fears unpredictable noises. That boy is autistic, and he is my son, Trey.

When you see a green balloon, I also want you to think of two Disney cast members. I don’t know their names (I wish I did so I could share their names and tell them how important their effort was to my family), and they don’t know me. But they went out of their way to help my son when the most important thing in his world was that green balloon.

On Saturday at the D23 Expo at the Anaheim Convention Center, Bob Chapek, president of Disney Parks and Resorts, gave a memorable speech in the grand hall. Near the end of his remarks, Chapek introduced a cast member, who took the stage and read part of a letter Disney management had received about a little boy and a green balloon.

Every time I see a green balloon now Ima cry💚 pic.twitter.com/DX5aLJBwr4 — abby @ d23 (@abbymuniz_) July 15, 2017

Last December, I wrote that letter.

I didn’t know it would make its way into Chapek’s presentation, or I would have had my entire family there.

I wish Trey could have been there to see what happened next.

After the letter was read, cast members took the stage carrying dozens of green balloons and sang “When You Wish Upon A Star.” They handed out green balloons in the crowd.

If you see me, bring a tissue and ask me about the green balloon. #D23expo pic.twitter.com/30ZTpvuOSn — As Mom Sees It blog (@AsMomSeesIt) July 15, 2017

I saw the reaction on Twitter, which was overwhelming. People were commenting through their tears. Someone posted a picture of a green balloon with the hashtag #austismawareness. People said they would never look at a green balloon the same way.

The following is the full letter I wrote to whom it may concern last December:

Thank you Disneyland …

These long days – even at the Happiest Place on Earth – can be tough. My son, Trey, is 6 years old, and he’s autistic. While most parents look forward to a day at Disneyland as a little slice of heaven, it’s not always that way for my wife Nancy and I. Trey sometimes responds negatively to noises, to crowds, to chaos. He often growls and screams, covers his ears and cries if someone bumps his stroller or he is surprised. In the past, we’ve had to leave Disneyland before noon because the stimulation is just too much.

We would do anything to try to keep him focused on having a good time.

This time, we entered the park at 8 a.m. and he told us almost immediately that he wanted a balloon. Not just any balloon. It had to be a clear balloon with a Mickey Mouse inside. And that Mickey Mouse had to be green – his favorite color. We tried to explain that it’s better to get a balloon on the way OUT of the park at the end of the day, so we don’t have to carry it around and risk losing it.

We made a deal with Trey. If he didn’t scream or cry, if he was nice to other people in line, if he didn’t run away from us – then, at the end of the day, we would get him a green Mickey Mouse balloon.

And I am here to say miracles do happen.

It wasn’t long before Nancy and I both commented that this was the best day. It may have been the happiest day of Trey’s young life. We adopted him at birth, and it has been an endless cycle of psychologists and psychiatrists and medications. But on this day, he was happy. The only ride he had ever tried in previous trips to Disneyland was “It’s a Small World.” Last year, he threw a fit outside because he was scared. This year, he not only rode Small World, he rode the submarine, the Mater ride (twice), several rides in Bugs Land and the Jungle Cruise.

Nancy and I kept looking at each other in almost disbelief. “Best day ever” we mouthed to each other many times.

We made it through lunch at Flo’s without incident. We amassed 29,000 steps and 14 miles on Fit Bit. Unbelievable. Then, we ended the day on Main Street where we saw Santa Claus. We went inside Gibson Girl to get ice cream.

It was dark, and Trey said he was tired. He didn’t want any ice cream, he said, because he wanted that green balloon.

YES, we told him. We hugged him and lifted him up and celebrated the best day ever. We walked down Main Street toward the exit. Stopping at each souvenir shop to get that congratulatory balloon.

But they don’t sell balloons in those shops.

They told us we had to find a walking balloon salesman on Main Street. We looked down the street, which was a mass of humanity, and we saw no balloons for sale.

No way. This couldn’t be happening. Children were walking past with balloons, some of them were green. Trey was starting to get a little upset.

So Nancy promised him she would find him a balloon. I kept Trey in the stroller by the flag pole as she went back down Main Street with determination.

I kept Trey busy listening to the Dapper Dans singing Christmas songs. But mommy wasn’t coming back. I tried to change the deal. What about Mickey Mouse ears with his name on them? I would have given him anything.

No, he said. And he started to get upset.

We didn’t know it at the time, but Nancy had found two Disney cast members. She asked about balloons and after some calls on a walkie talkie, she was told that there weren’t any more balloons for sale.

The two employees must have been mothers. They must have seen the horror on Nancy’s face. They told her to wait there and one of them took off trying to find a balloon.

Meanwhile, the Dapper Dans finished their set. It had been a half hour that Nancy was gone. Trey was beyond restless.

I was sweating.

Suddenly, he jumped out of the stroller and ran away.

This was it. I was going to have to chase him down and grab him and apologize for the screaming.

“Trey, stop,” I yelled.

But he kept going. He ran through several people on Main Street.

And into Nancy’s arms.

She was holding a clear balloon with a Mickey Mouse inside. IT WAS GREEN. Trey was jumping for joy. I threw my hands in the air like Nancy had just won us the Super Bowl.

We will never forget that green balloon.

Nancy said she hugged the two cast members, thanked them and told them “Merry Christmas” because she didn’t know what else to say. They didn’t charge her for the balloon.

To us, that balloon, that day, that ending … will always be priceless.