"I saw this principle in operation when I visited the Dohnavur Fellowship in India. There, day after day, year in and year out, Indian women (mostly single) care for little children, handicapped children, infirm adults, old folks. They don't go anywhere. They have none of our usual forms of amusement and diversion. They work with extremely primitive equipment - there is no running water, for example, no stoves but wood burning ones, no washing machines. In one of the buildings I saw this text: "There they dwelt with the King for His work." That's the secret. They do it for Him. They ask for and receive His grace to do it. I saw the joy in their lovely faces."
Keep a Quiet Heart, page 225-226
The reference quoted is 1 Chronicles 4:23