On a typical New York City day, David J. Polly grabbed a cab en route to Grand Central Station. A few minutes into the ride, a car jumped lanes and if it hadn’t been for the quick reflexes of his driver, they would’ve had an accident.

It took David a minute to regain his composure. But seconds later he came to the edge of losing it again when the reckless driver started throwing f-bombs at David’s driver.

David was in utter shock. But what really blew him away was how his driver responded. Instead of taking the angry man’s bait and arguing back, he just smiled and waved as if nothing had happened.

“Aren’t you going to say something?” David shouted. “It was clearly his fault! That guy’s lost his damn mind!”

Again, David’s driver just smiled. Then he looked at him through the rear-view mirror and said something that literally changed his life. Something David now refers to as “The Law of the Garbage Truck” —

“Many people are like garbage trucks. They run around full of garbage, full of frustration, full of anger, and full of disappointment. As their garbage piles up, they look for a place to dump it. And if you let them, they’ll dump it on you. So when someone wants to dump on you, don’t take it personally. Just smile, wave, wish them well, and move on. Believe me. You’ll be happier.”

Don’t let the actions of others dictate your day

One of the few certainties in life is that people will do things that piss you off. They’ll cut you off in traffic. They’ll snap at you for no reason. They’ll leave nasty comments on your articles.

Every single one of these things is out of your control. But what you can control is how you respond. You can fight back and run the risk of allowing that single incident to not only negatively affect you at the moment but also dictate your mood going forward. Or you can steal a line from David’s cab driver and smile, wave, and get on with your day.

• Do I really want to get involved in this?
• Is this worth getting upset about?
• Is this how I want to spend my day?

If the person who pissed you off is someone you care about, it’s worth asking yourself if there’s something going on that you don’t know about. The same goes for reminding yourself that you can be annoying too and giving them a pass. Sometimes even, a fight may be the best thing you can do to clear the thick air.

But if it’s a random person who decided that today is the day they’re going to take a leak in your Cheerios, there’s absolutely nothing wrong with choosing to skip breakfast.

The best part about getting older is patterns begin to emerge. One of the most glaring ones is that the happiest people I know don’t get worked up every time a jerk in a Jag makes them mad. They do this for a number of reasons. But primarily because they understand the more energy they waste on meaningless things, the less energy they’ll have for meaningful things.

It takes the average person 23 minutes to get back on track if they get distracted. Imagine how much time you’ve wasted in your life being attached to someone else’s mood and action.

Remember this as you head into the new year. Think of David’s driver. Remind yourself that a big part of your happiness depends on not allowing other people to make you miserable.

Then, the next time you feel your blood begin to beat red — rather than allow someone to throw their garbage on you, move on instead.

When it comes to life advice, few things are more important than developing the skill of restraint.

And over time, even learning how to smile at trouble.