The difference lies in the verb.
It was cold. = Telling
Amy shivered in the cold. = Showing.
An active verb connotates a showing sentence. But this isn't always true. I could have said, "Amy thought it was cold," and that does employ an active verb--but the beef of that sentence lies in the passive verb, not the active one.
To figure out what to show, ask: How do you know this?
It was cold. = A simple fact. Ask: how do you know it's cold?
Answer = Amy shivered.
Now, obviously, that's the ultimate in simplicity. You can't just stop there.
The difference between boring showing and good showing is in the emotion.
Amy shivered in the cold. = Boring showing.
Amy shivered: the cold seemed to reach all the way through her skin and into her heart. = Good showing.
Notice how they get longer? A picture's worth a thousand words--so to show that picture, it might take all thousand words.
Does this mean everything you write should be "showing?" NO. Let me say that again: NO. Sometimes it's just cold. Say it and move on. But if this is a point where you can and should show character development or enhance the story, show it.