Before Jonas escapes to Elsewhere, he is supposed to have been given every memory of strength and courage that The Giver can give him. These memories prepare him and Gabriel for the journey by helping Jonas lower his body temperature to avoid the search planes, and providing nourishment when they have no food.
Jonas has to escape on short notice when he finds out that Gabe is scheduled to be released.
There had been no time to receive the memories he and The Giver had counted on, of strength and courage. So he relied on what he had, and hoped it would be enough. (p. 166)
However, Jonas does use the memories he is given. Search planes are looking for them, and Jonas uses memories of snow to lower his body temperature and Gabe’s so the search planes cannot use heat sensors to find them. Jonas begins to worry because the more memories he gives Gabe and the farther he gets from the community, the fewer memories he has to sustain himself.
Jonas tries to use the memories to “recreate meals” when he cannot find food for himself and Gabe (p. 173). Jonas realizes he is starving. He has to make it to Elsewhere before what’s left of the memories is gone. Jonas regrets not having memories of courage.
Lowry, Lois (1993-04-26). The Giver (Newbery Medal Book) (p. 166). Houghton Mifflin Harcourt. Kindle Edition.
Since Jonas had the memory of snow, he was able to hide from the planes that were looking for him. Those planes used body heat to try to find Jonas. He made himself and Gabriel cold. Another way the memories helped Jonas during his journey is that he gave Gabriel the memory of deep, content exhaustion so they would both go to sleep. They needed energy for the ride ahead because they traveled at night only.