The Genius Murim Fitness Trainer

Ganghyeok is ruined. His gym business is failing and there's no way he can pay off his debts. But one night, while reading his favorite author's latest webnovel, he gets sucked into a world of martial arts fantasy and wakes up as a child monk in the Shaolin temple. There, he must apply his knowledge of modern fitness to survive their strict training, juggle the friends and enemies he makes along the way, and find a way to get back home. (Source: Webtoons)