We have spent a lot of time really think about our characters, about details that give us insight into their nature, etc. Remember that your character needs to have an arch of some kind still. With a declining plot, you will usually still have a rising character arch.
In thinking of setting, we are thinking of all of the things that are so important to knowing what is available and what constraints are placed on our character. We think of why they are in the situation they are in and if that is part of the story.
Read The Open Boat and compete assignment in Canvas
Complete Literary Naturalism - Setting in Canvas
Start thinking of how you can incorporate what we are learning to a deeper level in your survival story (I guess its not much of a survival story in some cases).