Johnson – who has been dating the Shark Tank panelist for over nine months – says their relationship works so well because it's based on friendship.
"We were friends first, and we got to know each other on a friendship level; I think that's really important," the dance pro, 39, tells PEOPLE. "That developed into something else, and it's really great. We're both each other's number one fans, and have respect for each other."
"I wanted to create this workout so people can do the dances you see on Dancing with the Stars in a cardio way," says Johnson. "Dancing is such a great form of exercise – you're having fun and you're getting fit. You don't realize you're working out!"
Johnson says people come up to her all the time saying they want to be transformed like the celebrities on the show, and her best advice is just to get out there and start moving.
"You just have to get started with it," she says. "Sometimes that's the hardest thing. You can do five minutes of exercise a day and build it up."
The stars on the show dance for eight hours a day – an amount of time unattainable for the average person – which is why she created the diet portion of her 5678 program to supplement the workouts.
"Obviously you can't do eight hours a day, so you have to watch what you eat," explains Johnson. "It's just a simple way to remember how to eat well – 5 is five sources of protein, 6 is to have six colors of the rainbow, 7 is to have seven anti-inflammatory foods, and then 8 is eight glasses of water to stay hydrated. It's not a diet where you have to cut out lots of things, it's more about having a healthy lifestyle and making it last."
She recommends cutting down portion sizes, and eating everything in moderation.
"That's an easy way to start changing the way you eat," says Johnson. "When you start depriving yourself of things, you start getting grumpy and you go back to eating bad things. This is this about introducing good foods in your everyday life."