“"You do your best, we do the rest." That fit the way I felt about God. I was going to give God my best and then it was up to God to do the rest.”

Source: Saving the World and Other Extreme Sports

The Almost Perfect State (1921)
Context: The best good that you can possibly achieve is not good enough if you have to strain yourself all the time to reach it. A thing is only worth doing, and doing again and again, if you can do it rather easily, and get some joy out of it.
Do the best you can, without straining yourself too much and too continuously, and leave the rest to God. If you strain yourself too much you'll have to ask God to patch you up. And for all you know, patching you up may take time that it was planned to use some other way.
BUT... overstrain yourself now and then. For this reason: The things you create easily and joyously will not continue to come easily and joyously unless you yourself are getting bigger all the time. And when you overstrain yourself you are assisting in the creation of a new self — if you get what we mean.

"Saina Nehwal Interview: Sportskeeda Exclusive" https://www.sportskeeda.com/badminton/saina-nehwal-interview-sportskeeda-exclusive (19 April 2012)

Speech to the Third Army (1944)

John Banville: Using words to paint pictures of "magical" Prague (2006)

As quoted in Life on the Circuit with Lincoln (1892) by Henry Clay Witney
Posthumous attributions

Thoughts suggested on the Banks of the Nith.
Bartlett's Familiar Quotations, 10th ed. (1919)

Don Soderquist “ Live Learn Lead to Make a Difference https://books.google.com/books?id=s0q7mZf9oDkC&lpg=pg=PP1&dq=Don%20Soderquist&pg=PP1#v=onepage&q&f=false, Thomas Nelson, April 2006 p. 173.
On Trusting God