When the whole mountain looks impossible, stare at your shoelaces and take the next step.

Scale is what makes things feel impossible, more than difficulty does. The whole of a large task arrives in your mind at once, and nobody can do the whole of anything at once, so the mind reports back that it cannot be done. Narrowing the frame to the next step is not a trick, it is the only accurate description of what you would be doing anyway.

When you freeze, ask what the very next physical action is. Open the file, write one line, put on the shoes. Do that one thing without looking up, and then ask again.