These quotations were taken from Stephen Covey's The 7 Habits of Highly Effective People. I greatly benefited from it and that is why I'm sharing these quotes. I will post a review of his book soon.
"We are what we repeatedly do. Excellence, then, is not an act, but a habit." Aristotle
"No one can persuade another to change. Each of us guards a gate of change that can only be opened from the inside. We cannot open the gate of another, either by argument or by emotional appeal." Marilyn Ferguson
"That which we obtain too easily, we esteem too lightly. It is dearness only which gives everything its value. Heaven knows how to put a proper price on its goods." Thomas Paine
"We must not cease from exploration and the end of all our exploring will be to arrive where we began and to know the place for the first time." T.S. Eliot
"I know of no more encouraging fact than the unquestionable ability of man to elevate his life by conscious endeavor." Henry David Thoreau
"No one can hurt you without your consent." Eleonor Roosevelt
"They cannot take away our self respect if we do not give it to them." Gandhi
"What lies behind us and what lies before us are tiny matters
compared to what lies within us." Oliver Wendell Holmes