Why do I always do what I want to do when I'm preparing a task?

I mean, I'm always preparing task for months, and every time I'm preparing a task I always do what I want to do. I don't understand what is wrong with me. I have a lot of time and resources to do my task, but I'm still preparing a task for months because I do what I want every time. I will be unhappy if I do a task for a long time when I always do what I want, so I should do a task before doing what I want or go to play. I know what I should do, but I'm still preparing a task for a long time.