Why do people experience a 'runner's high' after exercise?

People feel super happy and relaxed after running because their brain gives them a special reward.

Imagine you're playing your favorite game, and every time you do something awesome, you get a little treat, like a sticker or a piece of candy. After running for a while, your body sends out some helpers called endorphins, which are like tiny superheroes that make you feel good. These helpers travel to your brain and say, “Great job! You did really well!” and then poof, you feel happy and calm.

When you run, your body is working hard. Your legs move fast, your heart beats louder, and your lungs take in more air. This makes your brain think, “Wow, this person is really trying!” So it decides to send out those endorphins as a thank-you note.

It's like after you finish cleaning up all your toys, your mom gives you ice cream, it feels amazing because you know you did something good, and now you get a treat for it. That’s what happens in your brain when you run, you work hard, and then you get to feel happy!