Carnegie referred to Sir William Osler who co-founded Johns Hopkins University of Medicine, perhaps the most respected institute of its kind in the world today. In medical school, Osler was an unsure, worry addled young man who was constantly ruminating over the "what ifs" about his future to the point where it became a detriment to his health and the very future he held so dear.
However, there was one sentence that eliminated his anxiety and caused him to become one of the most successful people of our times: "our business is not to see what lies dimly at a distance, but to do what lies clearly at hand" With this statement, he went on to become so successful that it took thousands of pages of writing to document his life.
While speaking to a graduating class at Johns Hopkins many years later (has I've read), he stressed the importance of living in "day tight compartments", since worrying about the past, or the future, or even five minutes ahead can cause moments, even years and lifetimes to pass by.
As Andrew Carnegie stated in his brilliant book, think of your mind as a giant ship traveling the oceans. In order to keep it afloat and steady, you have to close the bulkheads to keep excess water wait from knocking it off kilter. If you are unable to close the bulkheads of your mind and stray from what is in front of you, you will wallow, flail and sink like the Titanic.
The secret to his success can be traced back to the bible. While I am a particularly religious person myself, I do ascribe to the messages of Jesus Christ who said "give us our daily bread." That was it, there was no tomorrow. All we could ask for is our daily bread. He also mentioned the importance of thinking nothing of the future, since there were enough troubles to deal with today.
So, when you have a mountain to climb, even if it is literally Mt. Everest, remember you are not climbing a mountain. You are taking one step and that's all you have to do, and all you should ever focus on, and the thought of the mountain will never overwhelm you.
PAST BOTHERS US
So many things took our time
We’ve left the real road out
But the facts had stolen our facts
The heavens calls us to live
What can we but do?
Daily the inclination to live
How can we pay our dues?
Something is calling us back
Our thoughts break upon us
We’ve relent in doing good
How can we go in this bus?
We’ve changed for another day
Our pasts are for true lesson
Though none of us knows change
We are bitter thinking treason
But this change must help