Ok, maybe the title was a bit over the top. That doesn’t detract from the truth, it doesn’t make it less valid, and it doesn’t lessen the importance of this basic personal development truth:

You need to take responsibility for your life.

Everything that happens to you, good and bad, can be traced back to your choices.
Sometimes this is obvious. My boss says something I don’t like so I punch him in the face. The result…I get fired (and maybe spend some quality time in the county lockup).
Other times it is more subtle. For example, you have a coworker that is usually late in turning in their part of a project. Do you confront them? Do you (professionally) say anything to them at the beginning of the project? Most people just let it slide to avoid the conflict. Guess what, your inaction is a choice that affects the outcome.