From what I have heard and what I have understood, I think, a personal mission or an individual purpose does not entirely exist.
We all have a common purpose and the purpose is life. Understanding who we are.
We all have an unique role to play in the grand scheme of things and if at all you do have a definite purpose, then it will reveal itself to you. Like Tesla and Einstein were born to be scientists.
Both of them did not go looking for a purpose but rather paid heed to what caught their curiosity.
That’s what we all should do. Pay heed to what grabs our attention, be humble, be good and do good.
Work earnestly and the rest will fall in place.