A 'Million Dollar Listing' says he learned a life-long lesson from becoming a millionaire at 26 - and losing it all in 6 months

Josh Altman is no stranger to big money.

The star of Bravo's "Million Dollar Listing Los Angeles" and cofounder of real-estate firm The Altman Brothers has sold over $1.5 billion in real estate, including the most expensive one-bedroom house in history, which sold for over $20 million.

Today, the 37-year-old has an estimated net worth of $10 million - but his journey hasn't been all rainbows and unicorns.

He first reached the seven-figure mark at age 26 ... and promptly lost it all by 26 and a half, he tells Farnoosh Torabi on an episode of her "So Money" podcast.

Ironically, it was a highly successful real estate investment - he and his brother put in $5,000 each to buy a house for $400,000 (with 100% financing) and ended up flipping it and making $200,000 - that precipitated the loss.

"We kept enrolling that money into bigger and bigger properties," he explains to Torabi - properties that they couldn't necessarily afford.

When the economy collapsed in 2007 and 2008, "I ended up getting stuck in a house that I couldn't move. I had lost all the money that we kept enrolling into the next one and into the next one."

"I thought that I'd never be able to get back to where I was," he continues. "But now, looking back, it was one of the best learning experiences I could have ever had. I learned I'm never going to be that person who's buying stuff that I can't afford."

Spending less money than you make is a simple concept, but one that many people struggle with - it's one of the reasons why many Americans are dangerously deep in credit card debt and have little to nothing in their retirement savings accounts.

Altman learned the consequences of buying more than you can afford the hard way.

Now, he pays himself first: "The second I get a check, I take half of it and put it into a separate account that I can't touch. That's my No. 1 rule. I don't even think I have more money than I have because it's already in a different account that I don't even look at."