Being alive is a risky business. No matter who you are, where you live, or how much privilege you enjoy, insecurity is the price tag on human existence, with danger, loss, and suffering close at hand even in the best of times. Science is finally catching up to what sages have been saying forever. Thanks to recent breakthroughs in MRI technology, neurologists are now able—for the first time in history—to observe the human brain in the act of feeling. This has revealed a phenomenon known as neuro- plasticity, which in turn has revolutionized how we think about personal change.