On July 4th 1952, Florence Chadwick stepped into the water off Catalina Island to swim across to the California coast. She started well and on course, but later fatigue set in, and the weather became cold.
After she recovered, she was told that she had been pulled out only half a mile away from the coast. She commented that she could have made it, if the fog had not affected her vision and she would have just seen the land.
She went back to her rigorous training. And two months later she swam that same channel. The same thing happened. The fatigue set in, and the fog obscured her view, but this time she swam with faith and vision of the land in her mind. She knew that somewhere behind the fog was land.