Destiny player and reddit user SerfaBoy needs to provide me with a few lessons in patience.
As you can see in the video above, the fella leveled to 40 by reloading the first mission A Guardian Rises.
According to SerfaBoy, this where Ghost wakes the player and tells then to get through the Wall and collect thier ship.
“Except I never collect the ship,” he said. “I go to Orbit and then loaded back in, only to kill all the enemies again. So long as Rahn lives, the mission never ends. So long as the mission never ends, I might be able to make it all the way to Level 40.”
We’ll, he did, and he breaks it all down for you in his thread on reddit. In it, he says he wanted to provide himself with a challenge, and he accomplished it.