WeCroak, Mr. Bergwall said, was born of Bhutanese folklore saying that to be happy, one ought to contemplate death five times a day. For the more than 9,000 users of WeCroak, most in their 20s and 30s, he said, there is no time like the moment to get a grip on life by embracing mortality. Hovering near the top of the App Store’s paid health and fitness chart, the app, which I first read about in The Atlantic, is an exhortation to mindfulness. “Meditation urges you to focus on your breath,” Mr. Bergwall sai