WeCroak (iOS, Android) is a bit morbid but I love it. At random times throughout the day I get a notification banner that says “Don’t forget, you’re going to die,” with instructions to open the app for a quote. All the quotes are about dying. The app is inspired by Bhutanese culture where one is expected to think about death five times a day to achieve happiness. So far my favorite quote to contemplate is a question from Pema Chödrön: "Since death is certain, but the time of death is uncertain, what is the most important thing?” — CD