"Metcon" workouts (metabolic conditioning) are not about strength-building or weight loss. They are about building vigor and endurance. A combination of HIIT Cardio and calisthenics, usually.
They are far better, and more fun, done in a group in a gym. Not 20 minutes, more like an hour with a 5-minute warm-up and 5 minutes stretching at the end.
Metcon Workout: Is It for You?