This father of 3 lost 45 pounds through the keto diet during quarantine

With the coronavirus pandemic keeping Americans at home, many have learned how easy it is to develop unhealthy habits like over-snacking or not exercising.

But Joe Mull, a 43-year-old father of three from Pittsburgh, has used his time during quarantine to develop a healthier lifestyle.

"The thing about quarantine is a lot of the distractions were no longer there for me," he told "Good Morning America." "The weight just started falling off."

Before the pandemic, Mull said he always had a toxic relationship with food and was on track to have a heart attack by age 50.

"I was miserable. I spent a lot of time being awful. I had no energy," he said. "I started to believe that I didn't have a lot more 'next times' left."

Instead of dwelling on the things that he felt negative about, he changed his mindset and turned to the keto diet to help him shed some weight.

On the keto diet -- with its focus on a low carbohydrate and high fat way of eating -- Mull went from eating a cheeseburger and French fries for lunch to having a salad with avocado and turkey and cheese on a low-carb wrap instead.

"I started on March 9th with a commitment to keto and just took it one day at a time," he said. "I said I’m going to show up today and eat this way. I’m going to be active, and at the end of every day I got to experience that feeling of accomplishment."

"And then when you start stacking days together like that, you get momentum," said Mull.

In a matter of months, he dropped 45 pounds.

"I have to focus on making a small, daily commitment, which is ironic because I make a living speaking about commitment in the workplace," said Mull. "I had to apply the same lessons to myself that I teach managers across the country, which was to focus on making small changes to your routines and your habits that will produce the results that you want."

The hardest part about following the keto diet for Mull has been resisting the foods he has in the house for the rest of his family and instead choosing what he describes as "real foods, whole foods that are low in carbs and low in sugar."

"I’ve got three kids at home under the age of 10 and so we have snacks and treats in the house and so it’s learning how to recognize those urges, pause, walk away and choose something else," he said. "That’s something that will always be a struggle but that I have to just take one day at a time."