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: I was very out of shape. Sentence2: I needed to start working out. Sentence3: My doctor told me to start slow. Sentence4: I began with doing jump ropes. Sentence5: After weeks of jumping rope, I began to feel excellent.
I (myself), Doctor