Procrastination

In order to survive, man needs to perform certain tasks, like work for money, or buy groceries for food. Yet it is a part of human nature to do what one desires, such as play a game of football, surf the web, or read a book. So obviously, some things that are neccessary conflict with thing that we want to do. Now, it is in everybody's best option if one does the things that will keep one alive longer and inrease one's chance of survival. Yet we have things like procrastination, and neglect which make us not do these things.

Why is it a part of human nature to have humans neglect the things that will increase their survival rates?