Your "Y" is simply why you exist. It does not need to be a larger than life reason. It's simply how you define or believe "Y" you are here.
A good example might be to set a better example for your kids than your parents did for you. Or to continuous remind people to not stress over problems that can't be changed.
When you are young, having a "Y" is not important. Getting involved in things that add value to your life and others is important. Try new things. Learn to listen to your inner voice. Use the resource found on the purposelyy.com site to learn Why You Matter. Even try helping others reach their purpose by becoming a Resourcer.
Your "Y" can not be taken, it is for you. There is no competing with your true destiny, whether you decide or if it's already decided. Just work towards your passion and Purposelyy will guide you further than you could have imagined.