Definition: In this task, you will be given a short story. One sentence from the story is chosen. Consider the events that happen before that sentence, or are likely to have happened before it. Does any of them directly cause it, or simply make it possible? You should write your answer in the form " A >causes/enables> B". Try to use phrases and sentences from the story to compose your answer when possible.
Input: story: Billy loved being active. He did fifty push ups a day. Until one day he hurt his arm. He was very sad. However, he decided to work out his legs to stay in shape.
 selected sentence: Until one day he hurt his arm.

Billy does fifty push ups every day >Causes/Enables> He hurts his arm