The ability to critically analyse your future is essential for your happiness, not because you will find happiness in your future but because you will be happy with yourself on your journey into your future.
You start by answering three questions. Where are you going? How are you getting there? Why do you want to go there?

Each question needs to be answered, and each question is important. However, I believe the why question is the most important because if you can’t logically decide why you want to be somewhere, what’s the point in going there in the first place. Which leads to the following sentence.
If the answer to your why question doesn’t make you happy, then you need to change your destination until it does.