A man was sleeping at night in his cabin when suddenly his room filled with light. An angel appeared, showed a large rock in front of his cabin and asked him to push against the rock with all his might.
This the man did, day after day. For many years he toiled from sun up to sun down, his shoulders set squarely against the cold, massive surface of the unmoving rock.
Nothing happened. And he decided to make it a matter of prayer.
“Lord I have labored long and hard in your service, putting all my strength to do that which you have asked. Yet, after all this time, I have not even been able to budge that rock. What is wrong? Why am I failing?”
The angel appeared again :
“My friend, I told you that your task was to push against the rock with all your strength. Never once did I mention to you that I expected you to move it. And now you come to me with your strength spent, thinking that you have failed. But, is that really so?”
“Look at yourself. Your arms are strong and muscled, your back sinewy and brown, your hands are callused from constant pressure, and your legs have become massive and hard.
“Through opposition you have grown much and your abilities now surpass that which you used to have.
“You learned the importance of discipline and training,
"This you have done. Now it is my turn, my task.”
And the angel moved the rock, showing to the man a beautiful path ahead.
[I originally read this story here.]