This is the goal of the traditional "Medicine Journey." That is, leave this place, go to a different place, get a Necessary Thing, and return to the place with the Thing.
Like some of our other motivations, this one seems on the surface to be exceedingly simple. That's at least partially because it is. By itself, it's as straightforward as they come, but can be complicated by the presence of multiple (sometimes conflicting) goals, as happens frequently when the MC is part of a group.
If group relationships and tropes are your thing, I highly recommend going to watch Overly Sarcastic Production's Trope Talk episode on the Five-Man Band for an in-depth analysis of protagonist group dynamics. It's pretty fantastic.
When your MC needs to Retrieve something, it's usually because the Thing is a solution to some problem or another. They need to get through a gate, and the object of the Retrieve goal is a key. They need to perform a spell, so they Retrieve an ingredient or a spellbook. They need to put their protag group back together again because without their missing buddy the Power of Friendship is broken, so they Retrieve their kidnapped/missing/damsel'd buddy.
When you're using the motivation of Retrieval in your story, it's usually more about the journey or the object than it is about the mission itself. The task is mundane, but the setting or the results are fantastic.
In addition, as mentioned earlier, the complication of multiple and sometimes conflicting Goals can make this vanilla Goal into something more interesting. You need to get the Holy Grail, but your estranged Father is along for the ride and his Goal involves trying to "bond" with you, which means he's getting in the way. Maybe you need to get the key to open the gate, but the key is being guarded by a monster that used to be your MC's big brother, and your MC has issues with stabbing said former brother in the face.
It's a mix-and-match game, and that actually makes me think that it would be fun to make a set of motivation dice that you could roll for a character group: you have three characters, but this one's Goal is to gain power while those two both want to retrieve a Thing. How do those three characters work together, or do they? Does their protag group fall apart, or does one of them turn into the villain?
The world is your oyster, as they say. Who says it's not polite to play with your food?
That's all this week. Stay awesome, Inklings, and as always, let me know how you think this Element should be handled or has been handled in the comments. InkFire, out.