What decision does Lennie from Of Mice and Men make, and what is the consequence of his decision?

At the end of the book, Lennie makes the decision to hide in the brush near the Salinas River after he has mistakenly killed Curley's wife. He says to himself, "I di’n’t forget, you bet, God damn. Hide in the brush an’ wait for George." He recalls the advice that George gave him to hide in the brush near the river if there is any trouble. The consequence of his decision is that George knows exactly where to find Lennie, and he finds him before the other men from the ranch do. He decides to shoot Lennie out of mercy, while telling him the reassuring story about the ranch they are going to have with rabbits. While this decision is excruciating for George, he hears the other men arriving in the brush, and he knows that he must shoot Lennie before other men come and Lennie is subjected to a much worse and more drawn-out punishment.