"Man is the one who decides his own destiny." Pull yourself up by your boot straps is a phrase that evolved from the concept that a person can choose and those choices are the most important factor in what determines the outcome of that person's life. And to a large extent this is true, but like pure determinism, pure free will does not consider all possibilities of causation. For example, a man is an alcoholic. It's too simple to say he's an alcoholic because he chooses not to stop drinking. Maybe his father and grandfather were both drunk, or he drinks because his significant other drinks. Maybe he drinks as self-medication for a psychological disorder because alcohol is cheaper than real medicine. Biological, social, psychological or even economic factors could have an effect on your addiction. Neither free will nor determinism are useful to use in their purest forms, because in these polar positions no theory can explain the fact that both theories have an effect on one's life.