The rubble has to hauled out. The tunnel has to be shored up. There's going to be the inevitable cave-ins. At times you're battling your aching body and your strained emotions as well as the rock. At times, you feel as if you can't go on.
Nothing is guaranteed.
Sometimes you'll take a wrong turn or your tools will break or you'll faced impenetrable hard rock or can't dig deep enough with the tools you've got. But, if and when we get down to the bedrock of that student's human potential we strike it rich. Make it a good day.