A recent issue of New Scientist has a headline article on "The Meaning Of Life". It describes research showing correlations between a sense of purpose and various positive attributes such as health and happiness. It then touches on a few ways people can try to enhance their sense of purpose.
Unfortunately the second paragraph gives the game away:
As human beings, it is hard for us to shake the idea that our existence must have significance beyond the here and now. Life begins and ends, yes, but surely there is a greater meaning. The trouble is, these stories we tell ourselves do nothing to soften the harsh reality: as far as the universe is concerned, we are nothing but fleeting and randomly assembled collections of energy and matter. One day, we will all be dust.
Quite so --- assuming a secular worldview. In that context, the question "what is my purpose?" has no answer. The best you can hope for is to grab hold of some idea, make it your purpose and refrain from asking whether you have chosen correctly.
To me, even before I became a Christian, that approach seemed unsatisfactory --- too much like intentional self-delusion. To conclude "there is no greater meaning" and carry on as if there is didn't seem honest.
Later I came to believe that Christianity is objectively true. That means God has created us for a specific (yet broad) purpose --- "to glorify God and enjoy him forever", in the words of the Westminster Shorter Catechism. The question has an answer. We'll spend eternity unpacking it, though.