Inhaler
Just Breathe
From the first time we see Mikey, he's using an inhaler to help with his asthma. Throughout the Goonies' adventure, Mikey can be seen taking quite a few drags off of it. But at the end, once their mission is accomplished…he tosses it away with a casual "Ahh…who needs it?"
Okay, so: asthma doesn't quite work that way. We'd assume his parents, once they got over the initial relief of seeing their son alive again, probably laid into him later about throwing away a perfectly good inhaler.
But what's the point of this inhaler toss? Why did the filmmakers decide to plant this detail if the inhaler never plays an important role in the story, and Mikey just throws it away at the end?
Well, in the context of an adventure story, having trouble breathing is a definite sign of weakness. Needing the assistance of a device in order to make your lungs function properly is seen as a flaw. (Hey: we didn't say this logic was good; we just said it was present.)
When our story starts, Mikey's weak and untested. He's a Goonie only by name. But throughout the course of the story, he gains confidence, overcomes his fears…and grows up a bit in the girl department, too.
The Mikey that comes out of the tunnels is pretty different from the one who went in. He's more of a man and less of a boy; he's courageous and doesn't need as much help getting the job done. So, because he's matured and become more self-sufficient, he's "outgrown" the inhaler and discards it like yesterday's trash.
Once again, though, we reiterate: asthma doesn't work that way. Asthma doesn't hold people back from having grand adventures; you can change the world without chucking out your much-needed inhaler.
Just ask Kristi Yamaguchi. Or Billy Joel. Or Elizabeth Taylor. Or Orson Welles. Or Edith Wharton. Or Che Guevara. (Source)