That which most people think can't be done

"The man who makes a success of an important venture never wails 
 for the crowd. He strikes out for himself. It takes nerve, it takes a 
 great lot of grit; but the man that succeeds has both. Anyone can fail.
 The public admires the man who has enough confidence in himself
 to take a chance. These chances are the main things after all. The
 man who tries to succeed must expect to be criticized. Nothing
 important was ever done but the greater number consulted
 previously doubted the possibility. Success is the accomplishment of
 that which most people think can't be done." - C. V. White