Given the task definition and input, reply with output. In this task, you're given a four sentences of story written in natural language. Your job is to complete end part of the story by predicting appropriate last sentence which is coherent with the given sentences.

Sentence1: Tim wanted to learn astronomy. Sentence2: He wanted to go into outer space. Sentence3: However he was to young to be an astronaut. Sentence4: This news made him sad.
Tim worked hard in school to become one.