Answer: Because you realize you have something to do and you don't do it.
Explanation: In procrastination, you are aware of your responsibilities but you are always looking for an excuse for not doing it. But deep inside of you, you know you are just avoiding it and feel bad because you know you have to do it but don't want to.
Procrastination is an issue that a lot of people have. They don't want to be responsible and try to hide that reality.