The Alchemist v/s Will

Had been into this confusion ever since I read 'the alchemist'.Destiny v/s will power.The alchemist strongly believes that 'if you really dream of achieving something,the whole universe conspires to achieve it'.He believes in 'omens'.The signs.He acts according to the God's will.Even in 'Godfather',Don Corleone believes that every man has one destiny.An artiste cannot become a mafia man,he supposed.This one completely contradicts with Adi dassler's statement-'Impossible is nothing'.But personally,I found it very hard against my conscience.At the end of the day,I should lay down in my couch with my heart contented with the work I had done that particular day.
What if I am destined to become something when I dreamt of becoming something else?Should I convince myself that this is what I meant to beor Should I fight with destiny with the help of my will to become what I wanna?
Dont know!