"You know, I was a guy that lost everything," he tells ET's Lauren Zima. "I hit rock bottom. You know, I was at the lowest, lowest, lowest point in my life to the point where I could barely get out of bed and today, I hop out of bed -- mostly because I have a very obnoxious alarm -- but I do hop out of bed, yeah."
"Things have changed," he continues. "Things are good. I'm really happy."
Tarek credits getting out of his slump to hard work.
"It's like anything in life; I just put a lot of work into myself and really focused on trying to become the person that I've always wanted to be," he shares.
When asked if his new girlfriend, fellow real estate expert and TV personality Heather Rae Young, had anything to do with his turnaround, he responds, "Definitely."
"Well, this is the first time in three and a half years I'm, like, officially dating," he points out. "I have a real girlfriend, you know? It's like, it's new, it's fun, it's exciting."
And he has a few wise words for those also dealing with personal struggles.
"You know, a lot of people talk about working hard in business and in life, I think it's most important to work on yourself," he stresses. "So, I think anyone who's out there going through any struggles or dealing with any issues, I think it's really important to take care of yourself first so you can take care of others."
"You know, it's a combination of many different things -- therapy, working out," he adds about his own work on himself. "I was dealing with a struggle because of my medications from my cancer. Some of the side effects I had dealt with were causing anxiety, depression, all these different things, so there were a lot of things involved to get me to the place that I'm at today."
The 37-year-old reality star is certainly keeping busy, and he spoke to ET about his new projects aside from Flip or Flop.
"So, Flip or Flop obviously is the main one and then Tarek's Flipside is a digital series which is on HGTV.com, and it kind of shows people how I live outside of being the house flipper guy, so I had a really fun time doing it," he shares. "Like, they roasted me. We did an episode where it was like mean tweets, we did shooting with [my] kids. We had so much fun filming with the kids and we talked about my personal life and then my cancer struggles and I think Tarek's Flipside the digital series, it came out great. It's probably my favorite project I've done for many different reasons."
He also previews his new HGTV series, Flipping 101 w/ Tarek El Moussa, and shares what's going to keep it interesting. The show will follow Tarek walking individuals through the ins and outs of a successful flip.
"To be honest with you, when I was first approached for the show I was thinking, Well, it's going to be boring," he admits. "I'm just going to stand there and tell people what to do and they're going to do it because I've done close to 500 houses. Totally wrong. So, I did the pilot, I was like, 'You have to do A, B, C, D,' and I come back to the house and they did Q, Y, Z, R. Like, it made no sense. Like, they didn't listen to anything I said, and I'm like, 'What made you do that?' They're like, 'We thought that would be better.' I'm like, 'How many houses have you done?'... 'Well, one.' I'm like, 'OK,' but they were like, 'I've seen a lot of shows like Flip or Flop' and I'm like, 'OK...'"
Through it all, Tarek's No. 1 priority is definitely his children with Christina -- 8-year-old daughter Taylor and 3-year-old son Brayden.
"They really do have a lot of support from me and my family, Christina and her family," he says. "They are very loved and they know they're very loved, which is very important for them to live a great life."
Flip or Flop airs Thursdays on HGTV.
ET spoke to Christina in May, when she revealed how filming the current eighth season of Flip or Flop with Tarek was unlike previous ones. Watch the video below for more: