Personal training is one of the most effective ways to get fit. Ray, a new AI-native app, is meant to feel like the real thing at a fraction of the price. When the new year rolls around, many people will resolve to get in better shape. Last year, Americans poured $44.8 billion into the fitness industry, flocking to gyms and buying at-home fitness equipment. But it usually takes just two weeks for people to abandon their goals. Gym memberships go unused. Peloton bikes collect dust.