Muscular man exercising doing sit up exercise. Athlete with six pack, white male, Outdoor training. Sports and healthy lifestyle. Bearded black-haired guy doing crunches Outdoors Shutterstock Image - Muscular man exercising doing sit up exercise. Athlete with six pack, white male, Outdoor training. Sports and healthy lifestyle. Bearded black-haired guy doing crunches Outdoors - ID: 666090562