Until 2013, Wang Yin never imagined that he would quit his prestigious, well-paid job in banking and start a new career in China's underdeveloped fitness industry.

Just two years later, the 30-year-old owns a booming fitness service comp-any, Shanghai Fit-start Network Technology Co, and also runs two fitness platforms on social media that have a combined following of more than 1.2 million.

The time Wang spent in the gym during a three-month gap between jobs changed both his mind and body completely. "The rewarding paycheck, five-star travel and elite social status made the decision to quit my job a tough one. But when I saw my potbelly and sometimes felt lethargic, I started missing the old, energetic days in college, playing basketball all the time. So two years ago, I joined my wife to hit the gym regularly," he said.

As he witnessed the physical and mental changes he was undergoing, Wang became addicted to working out, and also started sharing his training tips on social media platforms such as WeChat and Weibo. His posts attracted a large number of followers, who were all hoping to get into better shape.

The deeper Wang dug into the health and fitness industry, the bigger the business potential seemed - especially via social media and online marketing, which are now playing increasingly prominent roles in everyday life.

"Showing selfies of six-pack abs or a firm butt has been a trend on WeChat and Weibo for a while now, reflecting a growing public awareness of healthy lifestyles in China. That's why I was confident our services would make a mark in the digital-age fitness market," he said.

Wang's team, including professional trainers, sports-science specialists and nutritionists, uses an O2O (online to offline) business model to offer tailor-made workouts and diet plans to every client that signs up for a 1,599 yuan ($258) six-week fitness camp the company offers on WeChat's e-commerce platform.

Clients with similar physical conditions and fitness demands are placed in the same WeChat networking group, and are required to post photos proving they've executed their daily workout at home, which is overseen and guided by a Fit-start trainer online.

Offline workouts are regularly held at Fit-start's gym in downtown Shanghai to check clients' progress and improve communications. "It's hard to work out at home alone, but when you have companions who motivate you and share everything with an online social group, it makes it much easier to carry on," Wang said.

Since the company was launched six months ago, Wang's team has helped approximately 3,000 customers achieve their personal goals, either losing weight or building muscle. The numbers are impressive for a startup.

"I just hope to provide customized services through an accessible online platform for people who are keen to get into better shape and lead a healthier life, but haven't achieved them in the traditional way. Hopefully it will continue to consolidate my career in the booming fitness industry," he said.