Graduate school is not easy, but it's definitely fun - otherwise how could you survive 5 years of hard work? An important part of grad student life is choosing a topic to work on that will treat you well - you will enjoy woking on it and you will generate new knowledge (in units of posters, presentations, papers, talks, even books). Uri Alon gives tips on how to choose a good scientific problem - a short read that can save you some pain later in your career!