Joe Bennett, AKA the Hypertrophy Coach, is a thriving fitness coach who loves muscle building and coaching. With this, he came up with combining what he loves with what he is passionate about, thus becoming a fitness coach. According to him, to become successful in building a career around your passion, you must first leverage it and never stop learning. Also, you must learn how to earn buyers, not followers, through social media strategically.
Source: http://breakingmuscle.com/fitness/how-to-develop-a-coaching-career-doing-what-you-love