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: Sam decided he wanted to ride his bike to work to get some exercise. Sam didn't often ride his bike and had forgotten how to use the gears. Getting to work was simple since it was all down hill. Going home was difficult since the ride was all uphill. He arrived home exhausted and decided to practice gear-shifting.
 selected sentence: He arrived home exhausted and decided to practice gear-shifting.

Sam bikes uphill >Causes/Enables> Sam arrives exhausted