Before Melissa Alcantara became "Fitgurlmel" — the incarnation of a vibrant celebrity trainer who's helped whip Kim Kardashian into shape — there was just Melissa, a self-described "yo-yo dieter" who drank and smoked too much. The difference now is that the current version of Alcantara gained strength in a place not usually associated with building muscle and trimming fat: Her mind. "It's all in your head," the Bronx native told CNBC Make It. "It's all mental, especially when your goals and expectations are high." Although Alcantara is known today as a health and fitness expert she was once a depressed drinker and smoker. The 33 year-old knew she needed to change her lifestyle, after she gained 70 pounds during her pregnancy. At the time, she weighed 196 pounds and was not able to get rid of her baby weight. Alcantara said she's always been a "yo-yo dieter" and falling victim to binge eating. She also overindulged in cigarettes and alcohol, she added — until, of all things, a TV infomercial prompted her to change her life.

While watching television several years ago, she spotted an infomercial promoting a program that would leave great results. That program was Insanity Beach Body. "I'll start on Monday," Alcantara, sounding like many others who take a vow of fitness, only to procrastinate. Three more Mondays followed before she finally awoke at 5am one morning to begin the program's diet and workout plan. In 60 days, she finished the program 40 pounds lighter, and forced her to take ownership over her health. "I didn't know I had control," Alcantara said she learned from the program. "I didn't know I controlled what I put into my body." In December 2015, she decided she wanted more than just being skinny. A month later, she began preparing for a body building competition, which meant controlling her food portions and lifting heavy weights. "I became addicted to results," Alcantara told CNBC.

Melissa Alcantara, fitness trainer Source: Melissa Alcantara

She prepped for 17 weeks and won in two separate categories: Miss Figure and Miss Best Physique. It also opened up new doors for her career-wise. Alcantara had been working as a waitress, and because of her fit appearance, people would always ask her if she was a trainer or a dancer. It prompted many people to ask her if she could train them. Her dedication led to a wide array of business partnerships and a wide social media following that's exploded to over 340,000 on Instagram and 12,000 on YouTube. Most of that was the result of a fateful email she received in May 2016. The message in question was from one of Kim Kardashian's producers who later called and asked if she can train the "Keeping Up With the Kardashians" star, who was inspired by Alcantara's personal journey and work ethic.

Melissa Alcantara, fitness trainer Source: Melissa Alcantara