Gayna Pealling was taking a train trip with her two children when, suddenly, a day of travel turned into one of panic when her 5-year-old son began having a meltdown in his seat.

Her little boy, Jack, is autistic and has ADHD. He wasn't enjoying the long train ride anymore, and it was clear that he was overwhelmed, and acting-out.

Gayna struggled - until a young man walked over and sat down with her and the two youngsters. She didn't know it yet, but the 21-year-old man was about to save the day for everyone.

When she saw what the man named Dan was doing for her son, she just had to post a photo of the encounter on Facebook to thank him for everything.

Click below to find out what happened when the young stranger approached Gayna's children… (Photo by Gayna Pealling, Facebook)