19. These are the best years of your life.

Whether or not your young adulthood does in fact turn out to be the best part of your life by one measure or another, these probably are the years when you will be the healthiest, most energetic, and most capable of taking on challenges. This is the time to try, fail, and try again, to explore your options and discover work that you enjoy. Some of that energy would certainly serve you well in the energy-draining atmosphere of graduate school, but is that where you want to spend it? You really are only young once. Do you really want to start down the graduate school track from which it can be so hard to remove yourself? (See Reason 11.)

You can start a graduate program after you have tried something else first. For that matter, you can try two or three or four things first. In the process of giving something else a chance, you may discover your life’s calling and settle into a livelihood long before you would have finished graduate school. Having secure employment and income in your twenties gives you more flexibility when it comes to starting a family than you would have if you were to emerge from graduate school at 30 without any savings, and quite possibly in debt. Moreover, if you choose to start graduate school after working and saving for a few years, you can give yourself a monetary cushion that will improve your standard of living in graduate school and give you some peace of mind, which is a rare commodity among graduate students.