Those who say it can't be done are usually interrupted by others doing it.

Those who say, 'It can't be done,' are usually interrupted by others doing it.

Those who say it can't be done are usually interrupted by others doing it.

People who say it cannot be done should not interrupt those who are doing it.

The world is moving so fast these days that the one who says it can't be done is generally interrupted by someone doing it.

Pessimists are the people who have no hope for themselves or for others. Pessimists are also people who think the human race is beneath their notice, that they're better than other human beings.