Alright, little buddy! This is about exercise, which is like playtime but can be super duper intense. Some grown-ups did a study to see what happens to our bodies when we play really hard, like running or carrying heavy things.

They found that when people exercise very vigorously, their bodies might get a bit tired in a way that makes it easier for them to catch a cold. It's like their body's superhero team, called the immune system, takes a short nap.

But don’t worry! Exercise is still great because it keeps our bodies strong and healthy. They just want to make sure we aren't pushing ourselves too hard all the time.

Isn't it neat how our body works hard to keep us safe, like a team of superheroes?