How we cite our quotes:
He started ripping the bark, using his fingernails at first, and when that didn't work he used the sharp edge of the hatchet, cutting the bark in thin slivers, hairs so fine they were almost not there. It was painstaking work, slow work, and he stayed with it for over two hours. Twice he stopped for a handful of berries and once to go to the lake for a drink. Then back to work, the sun on his back, until at last he had a ball of fluff as big as a grapefruit—dry birchbark fluff. (9.16)
Step 1: make a plan. Step 2: follow through. Brian is one determined guy. This is one of Brian's most striking characteristics—and one of the things that helps him stay alive.
He would take [the eggs] now and store them and save them and eat one a day, and he realized as he thought it that he had forgotten that they might come. The searchers. Surely, they would come before he could eat all the eggs at one a day.
He had forgotten to think about them and that wasn't good. He had to keep thinking of them because if he forgot them and did not think of them they might forget about him.
And he had to keep hoping.
He had to keep hoping. (10.43-46)
The idea that he's going to be rescued someday is really important to Brian. It's what allows him to keep hoping, and to find the strength he needs to keep doing what's necessary to survive. Is hope a necessary part of perseverance?
A good laugh, that—cleaning up the camp. All he did was shake out his windbreaker and hang it in the sun to dry the berry juice that had soaked in, and smooth the sand where he slept.
But it was a mental thing. He had gotten depressed thinking about how they hadn't found him yet, and when he was busy and had something to do the depression seemed to leave.
So there were things to do. (11.3-5)
More than once in the book, Brian relies on keeping himself busy and making concrete plans to help buoy his spirits. Just having a goal and the determination to improve his situation a little seems to help him keep truckin'.