While I can't prove that life is meant to be meaningful and fulfilling, I absolutely know that I want my life to be meaningful and fulfilling. I also know that I want that same thing for other people.

For the sake of argument, let's say that I am wrong; life is not meant to be meaningful and fulfilling. I will still choose to believe that it is. In this instance I'd rather be delusional and happy than sane and miserable. Furthermore, even if my happiness and sense that I have a purpose are a result of some sort of placebo effect, I will still be experiencing those things as if they are real.

For me it is only logical to approach life with optimism. I recognize that we will all face challenges, disappointments, and even tragedies. We can't control everything that happens to us. We can control how we react to the things that happen. I see no downside in approaching life as though we deserve to live the life of our dreams. Even if I spend my life pursuing my true purpose and I never find it, at least the pursuit gave me a focus and a sense of meaning.

"I firmly believe the Universe dreams a bigger dream for you than you can dream for yourself ... You've got to open yourself to the dream that the Universe has for you. You've got to discover your true calling."
Oprah Winfrey