What if you could stop worrying (or feel more confident, or less stressed) with just a few simple words? That’s the premise behind Habit Changers: 81 Game-Changing Mantras to Mindfully Realize Your Goals ($16, amazon.com), a powerful little book filled with one-line mantras meant to help you reprogram your brain. Inspired by a Tibetan Buddhist mind training practice called Lojong, author and executive coach M.J. Ryan has been using simple slogans with her clients to…