Impossible?

"Impossible is just a big word thrown around by small men who find it easier to live in the world they've been given than to explore the power they have to change it. Impossible is not a fact. It's an opinion. Impossible is not a declaration. It's a dare. Impossible is potential. Impossible is temporary. Impossible is nothing."
— Muhammad Ali

* We are the only ones who can decide whether or not something is impossible. We are the only ones who can set up imaginary limits for ourselves. Nothing is too hard that qualifies it for the term "impossible," unless we say so. After all how many people in the past have said that the things which we now enjoy in this day and age are impossible, and in the course of doing so have been proven wrong? We have so many modern marvels in our day because great men didn't give into the term "impossible." They persisted where others quit, and now what was once deemed impossible is as real and possible as anything else was then.

Some more quotes:
"Success seems to be largely a matter of hanging on after others have let go."
-William Feather

"Some men give up their designs when they have almost reached the goal; While others, on the contrary, obtain a victory by exerting, at the last moment, more vigorous efforts than ever before."

"When you get into a tight place and everything goes against you, till it seems as though you could not hold on a minute longer, never give up then, for that is just the place and time that the tide will turn."
-Harriet Beecher Stowe