At first, Ponyboy tries to convince himself that Johnny's death was not real. He tries to avoid thinking about Johnny's death in the hospital and Dally's death on the street.
... don't think. Blank your mind. Don't remember.
Later, when Randy visits him at his home, Pony tries to convince himself that none of the previous events had happened. He himself killed Bob, the Soc, and not Johnny, Pony told himself; and he wanted to believe that Johnny was still alive.
"Johnny is not dead... Johnny is not dead."
Pony promised Soda that he would be "more careful," but instead, after the court hearing, Pony seemed to stop caring about everything. His grades went down and he stopped eating ("Everything tasted like baloney.") When he was approached by a group of Socs at a neighborhood grocery story, he took a tougher stance than he ever had before.
I busted the end off my bottle and held on to the neck... "You get back into your car, or you'll get split."
Pony then advanced toward the Socs, and they returned to their car and drove away. Two-Bit, who was with him, begged him
"... don't get tough. You're not like the rest of us and don't try to be...
But Pony had a new viewpoint.
... if you got tough, you didn't get hurt. Get smart and nothing can touch you...
Pony threatened to drop out of school and get a job, but after reading the letter Johnny had written him, his outlook became clearer and more positive.