Pursuing Purpose

Purpose is an interesting concept that I sometimes find hard to define. Some people believe everyone's "Purpose" is simply to live a life of happiness, while others believe purpose is completing goals or reaching a certain status of success. My problem with Purpose is that while I believe every person has a purpose, I don't know if it's something that can be pursued or has to be reached. To clarify I think at birth every life was put onto earth to do something, but what this something is confuses me because is it something predestined like a person's purpose is to later become president or is their purpose to pursue that presidency and whether or not they end up actually becoming president doesn't matter, just the fact that they are working in the direction of that purpose. In The Stranger the character Meursault goes through life without a definite purpose, he simply does what pleases him in the moment and only when he is sentenced to be executed does he decide that his purpose is to die with people hating him. While a strange one, Meursault is able to come up with his own idea of what his purpose is, but is it one that was predestined or fated to happen without him knowing or were his own actions what led him to pursue that purpose? To show my predicament I'll give an example of my own life: ever since I was little my parents told me I could be an amazing doctor or president someday with my natural aptitude for math and intellect however I dismissed these ideas because I didn't see myself in either of those fields, but how am I to know that my predestined purpose wasn't to become what my parents believed I had been given the ability to be, and in not following this was I inherently pursuing my own purpose? And if I were to somehow still  become president or a doctor without actually intending to follow those paths would my purpose have been fulfilled, or would I have failed because purpose needs to be pursued? I think this problem is actually important to many people because I think everyone struggles to define what their life "means" and whether or not there life has any meaning at all. I think most people try to find meaning in a purpose and it ends up being an endless cycle of disappointment when people feel like they aren't meeting their own expectations but also can't come up with what these expectations should be. I think for me at least I am going to try and focus on the aspect of making myself happy rather than worry about whether or not I'm living up to what other people think I need to do. Through that I think it's easy to figure out what my purpose in life is and even if I don't at least I'll be able to say I lived my best life for me and I won't be in regret or despair being so focused on pursuing purpose.