Flex is a free mobile app that allows everyone to quickly build muscle or lose weight. You can find over 1000 top-rated workout plans, including muscle gain, fat loss, or strength enhancement. With Flex, you can easily create, share, and customize your personalized workout plans, learn how to perform various exercises, track your personal bests, and visualize your progress through charts. We also offer fun gamification features, challenges, and friendly reminders to help you build a workout habit. With the expertise of trainers and artificial intelligence, Flex's customized workout plans can help you exercise at the right pace and see results quickly. You can also fully create and customize your own workouts, training plans, and regular schedules, and then share them with friends. In addition to these features, Flex also provides an easy-to-use interface, automatic progress tracking, weight recording, calorie calculator, and music control.