I took a look into this, and the most common reference is "someone once said" or just "an old saying". Like yourself, I saw the reference to Corrie Ten Boom, and also Dr. Adrian Rogers and John West. I did not see anything to suggest that Lewis is the originator.
quote:What is the biggest obstacle facing the family right now? It is over-commitment; time pressure. There is nothing that will destroy family life more insidiously than hectic schedules and busy lives, where spouses are too exhausted to communicate, too worn out to have sex, too fatigued to talk to the kids. That frantic lifestyle is just as destructive as one involving outbroken sin. If Satan can't make you sin, he'll make you busy, and that's just about the same thing. ~ James Dobson
"If Satan can’t make you bad, he makes you busy. If we learn to say ‘No’ to good things, we are able to say ‘Yes’ to better things God sends our way." ~ Nationally-renowned speaker PhyllisWallace