One question: Why?

The one question, out of the many I have, that has stuck with me for a long time, is why do ANYTHING if we are just going to die anyway? Why waste time going to school? We're just going to die. We might as well do things we enjoy and travel the world so we make the most of life..because we are just going to die anyway. It just seems weird to think of doing anything when in the end, it doesn't even matter. What is our purpose? One night during a family dinner, probably like 5 years ago, my sister and I had this conversation. We got so into the question, that we started questioning doing anything. We were saying things like, "Why eat if we are just going to die? Why waste time sleeping if we are just going to die?" My parents thought we were crazy but we didn't! We thought we were making complete sense. Right? So that night we decided we weren't going to do any homework. We stayed up late and watched movies and had fun. We went to sleep at 3 am and woke up at 4 am. What was the point of sleeping more? After we woke up, we went outside and played soccer, showered, made a big breakfast, went to school late, slept in class (well I did), etc. What was the point of following the rules and doing the usual if we were just going to die? Well it took a toll on us after not doing the homework assignments and being too tired to do anything. So we learned our lesson, but it still didn't completely answer our question. Really? What is the point? What is the point of doing anything if we are just going to die in the end? What is our purpose here? Although frustrating, we have to go on with our lives..even if we are just going to die..