Daniel and Kelli Segars of Seattle run one of the most popular fitness websites in the world, Fitness Blender, out of their garage.

It's free -- and it's making millions healthier:

"We're just shy of 3.7 million subscribers on YouTube, and adding roughly 2500 to 3800 people a day,” said Daniel.

"We're just over half a billion views on YouTube [and] that's not counting our website at all,” added Kelli. "It's a big family!"

It all began when these two closed on their first house, got married, and then lost their personal trainer jobs -- all on the same weekend.

“It was 2008 so it was right when things start to crash it was total chaos, it was three huge life changes in like four days,” Kelli explained.

They decided if people couldn't afford personal trainers in real life, maybe they should offer their services for free -- online.

Soon, their authenticity and their solid coaching started getting noticed on YouTube.

"And we got our first AdSense, which is basically Google Ads for our site, and it was like nine cents. We got nine cents on our site and we were like, 'This is gonna work! We can do this!'" said Daniel.

It has worked -- now they make a living from those online ads -- which also serve another purpose.

"People will say, 'Thank God for the commercials,' because they need the water break, they need to catch a breath and whatnot,” laughed Kelli.

Today, Fitness Blender occasionally hires a videographer, but Kelli and Daniel still edit videos themselves. They also still use a studio light they built themselves from hardware store bulbs, foil, and white plastic garbage bags. It works as well as anything a photography supply place would sell at a fraction of the cost.

And they still keep their bloopers in the exercise routines. During the butt and thigh workout, Kelli kicks, then bobbles, and laughs, "Whoops! Gotta fall over at least once!”

It’s refreshing.

Working out is working out for these two -- Fitness Blender is now a multimillion dollar business.

"This is kind of a dream come true in the sense that I can technically make my own schedule,” said Daniel.

"It lights me up," said Kelli. "I'm full of ideas and I feel like I'm going to help people and it’s something that I feel passionate about, so I love that I get to pour myself into this."

And this couple agrees that the real reward is helping people all over the world get healthy -- one workout at a time.

Evening is your guide to Seattle and the Pacific Northwest. Watch it weeknights at 7:30 on KING 5 TV or streaming live on KING5.com. Connect with Evening via Facebook, Twitter, Instagram or email: eveningtips@king5.com.