You held the light rail door with your foot and told me not to run

I was running for the light rail in Downtown Phoenix with a very heavy bag and the doors were closing. A man stuck his foot in the door, held it, and smiled like it was nothing, for what felt like twelve very long seconds. I got on. He said, I did that once and learned my lesson. I thanked him. He said, do not run like that, I cannot always be there. He got off two stops later. I have not run for a train since. I have been early every day.