Everyone knows that a strong man is not the one who never falls, but the one who falls but then rises. In my own opinion if you want to reach your targets, the expression "never, never give up" should be your motto. Any significant victory or achievement of success requires an enormous investment of labor and time. We can see giant amount of evidences confirming this rule in our routine life, in history, art and science.
One of the most impressing stories about incredible fortitude and strong will appeares in the "Shawshank redemption" by Stiven King. This novella tells about a banker who spent 19 years in Shawshank State Prison for the murder of his wife and her lover despite his claims of innocence. He created an almost impossible plan how to escape this prison, and was realizing it step by step during being jailed. Having encountered a lot of obstacles on his long way to freedom, he passed through it with unreal self-possession due to irresistible desire to become free, cold calculation and fixing on "never give up". This story reveals us that human's abilities are much more wide than we think, and it inspires me to overcome the most difficult complications I have.
Besides, we can learn to never give up from the famous actors, who won the fight with stuttering. Brus Willis, Julia Roberts, Antony Hopkins are among them. They was struggling with this disorder by years and not only overcame it but became the well-known public persons, so-called "stars". But it wouldn't be so without support of their relatives and close friends; especially without hard working and boundless will.
In conclusion, I want to say, that there is nothing impossible, and if you want, your goals are clear and ways of achievement are pointed, the success is unevitable.