If critical periods aren’t quite so firm as people once believed, a world of possibility emerges for the many adults who harbor secret dreams — whether to learn a language, to become a pastry chef, or to pilot a small plane. And quests like these, no matter how quixotic they may seem, and whether they succeed in the end or not, could bring unanticipated benefits, not just for their ultimate goals but of the journey itself. Exercising our brains helps maintain them, by preserving plasticity (the capacity of the nervous system to learn new thing), warding off degeneration, and literally keeping the blood flowing. Beyond the potential benefits for our brains, there are benefits for our emotional well-being, too. There may be no better way to achieve lasting happiness — as opposed to mere fleeting pleasure — than pursuing a goal that helps us broaden our horizons.