If you have no confidence in self you are twice defeated in the race of life. With confidence you have won even before you have started”
Marcus Garvey — the Philosophy and Opinions of Marcus Garvey edited by Amy Jacques Garvey
That is a quote from the Philosophy and Opinions of Marcus Garvey edited by Amy Jacques Garvey. It is one of the most widely known quotes by him. It generates nearly 400 results in a verbatim search on Google books and produces nearly 5,000 results on a verbatim search on Google. It is one of many quotes which can be found in the book Emancipated From Mental Slavery: Selected Sayings of Marcus Garvey, the title of which is also another quote from him.

Emancipated From Mental Slavery: Selected Sayings of Marcus Garvey uses as its sources The Negro World Weekly Newspaper, The Blackman Magazine, and The Philosophy and Opinions of Marcus Garvey. The title is taken from the speech Garvey gave at Menelik Hall in Sydney, Nova Scotia on October 31, 1937 entitled the Work That Has Been Done and immortalized by Bob Marley in Redemption Song.
What’s most intriguing about the “Confidence” quote is how loaded with nuance it is. “Twice defeated” is basically a category for research in itself. Full of meaning, a closer look shows that defeat happens twice which seems to echo Shakespeare:

“A coward dies a thousand times before his death, but the valiant taste of death but once. It seems to me most strange that men should fear, seeing that death, a necessary end, will come when it will come.”
William Shakespeare “Julius Caesar”
The person who lacks confidence suffers two defeats, just the same as the coward. In the case of the self-doubter, their defeat happens first in their mind. Inevitably, that defeat then becomes real, because, their mind makes it so. This also references a quote from Garvey in the epic essay “African Fundamentalism” written while he was held hostage in Atlanta Penitentiary.

Likewise, the confident also have won, because their win is first in their mind and then becomes real. Psychology Today speaks of this as well. Amazing how some people need college degrees and Pee Aitch Dees to get what Garvey gives us for free or at least the price of a book.