Pick a nearby object and get right up close to it, just looking at one spot. Then, when you’re sufficiently cross-eyed, sit back while still looking at the object. Now step back a few steps and look at the object. If you want “extra credit,” get as far away from the object as possible while still being able to see it.
Notice that when you’re really close to something it’s hard to see the whole thing, but you can see finer details. Notice also that the farther you are away from something the fewer details you can see, but you can see how the details fit together.
In life, sometimes you need to focus closely on one spot. Sometimes you need to see a whole picture. Often you need to do both in alternation, stepping back to see the whole thing and getting close to find or tweak something.