“Ask anyone what makes them happy and they will tell you—after first perhaps mentioning all the usual X-rated stuff—that it’s the little things that matter,” Gerard Janssen writes in his intro for Cheerful in 100 Days, originally titled Cheerful in 3 ½ Months. Gerard wrote “Cheerful” under the small-in-size-but-mighty Dutch publishing house Uitgeverij Snor (“Snor publishers” in English), who Knock …