The great obstacle to progress is prejudice.

Doubt, fear and regret are the three villains of success. However, if you close the door on the first two, you will never have to worry about meeting the third.

Allowing, therefore, the great usefulness of the Government Schools, the Exhibitions, and the Museums both public and private, the question now arises as to what are the impediments to our future progress. The principal ones appear to me to be three.

The greatest obstacle to connecting with our joy is resentment.

We have in all things three great enemies: (1) devotion to material prosperity, national and individual; (2) love of sport and gambling in all forms; (3) apathy.

But by far the greatest obstacle to the progress of science and to the undertaking of new tasks and provinces therein is found in this — that men despair and think things impossible.

The greatest obstacle to pleasure is not pain; it is delusion. The principal enemies of human happiness are inordinate desire—the fantasy of attaining something that exceeds what the finite mortal world allows—and gnawing fear.

We see barriers to business as barriers to national progress.

But here’s the truth: the ultimate thing that stops most of us from making significant progress in our lives is not somebody else’s limitations, but rather our own limiting perceptions or beliefs.

Obstacles are those frightful things you see when you take your eyes off your goals.

the three Rs: resentment, rejection, and regret. As a human being living on planet Earth, you’ll experience all three at some point or another. These babies, above all other feelings, are the most insidious. They’re

The obstacles to peace are not obstacles in matter, in inanimate nature, in the mountains which we pierce, in the seas across which we fly. The obstacles to peace are in the minds and hearts of men. In the study of matter we can be honest, impartial, true. That is why we succeed in dealing with it. But about the things we care for — which are ourselves, our desires and lusts, our patriotisms and hates — we find a harder test of thinking straight and truly. Yet there is the greater need. Only by intellectual rectitude and in that field shall we be saved. There is no refuge but in truth, in human intelligence, in the unconquerable mind of man.

Pride, jealousy and possessiveness
3 pains of hell

Obstacles are necessary for success because in selling, as in all careers of importance, victory comes only after many struggles and countless defeats.