1 Nephi 8:24
Lehi views those who hold to the rod and press forward through the mist of darkness. These are they who come forth and partake of the fruit of the tree of life.
The best definition I can come up with for the mist of darkness is that as we attempt to pass gates or some sort of checkpoint we feel the headwinds of opposition. After passing those points we step into the mists of confusion. After passing those points we may not have a clear view of the next point to strive for. Those who grip the rod and press forward are those who, after passing these points, do what they know to do that makes for preparation in general. Things like daily scripture study. Then when the goal comes into view they do specific preparation (i.e. temple prep class to get endowments, recommend to get sealed etc.).