3. Purpose
One of life's biggest mysteries is life itself. How did we come into being? What is the purpose of life? Some people at adolescent stage of life feel that life has no purpose, and that we're simply small lifeforms that mean nothing and compared to the number of people in the world and how large the galaxy is, we are insignificant. (Feel free to add more ranting to the end of the previous sentence.)
As a child or 'young adult', life is pretty simple. You go to bed, you eat, you drink, you shower, you go to school, you do homework and you repeat. (Including various social acceptance sub-plots) Although, during the summer, many people haven't found activities to replace school, such as volunteering, tutoring, or work. The result is 3 months of meaningless 'hanging out with friends' and browsing the web.
