This simple act of kindness filmed on a train is going viral – can you spot what it is?

It’s so simple most people can't even see it.

Blowing up on Reddit today is this short – but beautiful — gif of an unidentified young man on the subway performing a very subtle act of kindness. Can you spot it?

Having trouble?

Don’t worry, you’re not the only one.

Pay close attention to the elderly passenger as she slowly sways forward as the car rocks back and forth. Notice how the guy ever-so-slightly reaches out his hand to protect her head from hitting the subway car’s metal pole.

OK sure, it’s a pretty small act of kindness, but it’s the type that make this world just a slightly more enjoyable place to live in.

It’s also the kind that goes viral — after being posted less than two hours ago, it’s already the #1 post on the front page of Reddit.