If Everything Is "Controlled By Destiny", Then Why..........................?

throughout my life , i have been hearing , whatever the mind can believe, the mind can achieve! that human being with a burning desire can win anything , and can affirm the subconscious! i wanted many things , with burning desire , still reverse happened! No if all is controlled by god, then all these motivational things are useless? all , that man makes his own life, thoughts , all is joke? Why? why? i am very sad?