Given the task definition and input, reply with output. In this task, you're given a story (which contains five sentences only). Your task is to find all the characters which are available in the given story.

Sentence1: John felt he was getting fat. Sentence2: He decided to start working out. Sentence3: He invited a friend to do it with him. Sentence4: They would motivate each other to do better. Sentence5: John and his friend achieved their goals.
His friend, John