Imagine you’re standing on one end of a very narrow valley, with sheer, unclimbable rocks to either side of you. You can’t turn back, and you can’t climb the rocks. You don’t even want to. Instead, you want to get to the other side of the valley. That’s your goal.
There are several problems, however.
First, between you and the other end of valley are all kinds of obstacles. There are pits, crevasses, huge boulders, dense thickets, and all kinds of obstructions. As a matter of fact, from where you stand to where you want to go, it looks pretty much impassable. At a minimum, it’s going to take much more work than you were planning on.