The obstacle is the way
Earliest we can find
This is the earliest source we can find for the idea. Said again in 7 books on our list: Chekawa Yeshe Dorje, The Seven Points of Mind Training (12th century), Ralph Waldo Emerson, Essays, First Series (1841), Orison Swett Marden, Pushing to the Front (1894), William George Jordan, The Majesty of Calmness (1898), Viktor E. Frankl, Man’s Search for Meaning (1946), Dale Carnegie, How to Stop Worrying and Start Living (1948) and Ryan Holiday, The Obstacle Is the Way (2014).
“for the mind converts and changes every hindrance to its activity into an aid; and so that which is a hindrance is made a furtherance to an act; and that which is an obstacle on the road helps us on this road.”
Full text read.
Marcus Aurelius, Meditations 5.20, tr. George Long (1862).
Project Gutenberg eBook #15877, gutenberg.org/