Heidi Montag and Spencer Pratt have learnt to be ''really diligent'' about their money.

The former 'The Hills' stars admit they blew their $10 million fortune on lavish shopping sprees, plastic surgery and the blonde beauty's failed music career because they once thought they were on a par with Jay Z and Beyonce.

The 27-year-old model told In Touch Weekly magazine: ''It's hard. We have to be really diligent about what we spend. Now I can spend like $100 at Victoria's Secret. I feel like a different person.''

Spencer, 30, added: ''We thought we were Jay Z and Beyonce. In hindsight we should've been more low-key.

''Every time we'd go out to eat, we'd order $4,000 bottles of wine. Heidi was going to the mall and dropping $20,000-$30,000 a day.''

The former 'Celebrity Big Brother' stars, who wed in 2009, spent most of their money funding Heidi's album 'Superficial,' which was only downloaded 6,000 times.

Meanwhile, Heidi, who shocked her fans after she underwent 10 plastic surgery procedures in one day in 2010 and recently had a breast reduction, hopes to have a daughter one day and plans to encourage her never to change her appearance.

She told Life & Style magazine: ''I would definitely advise her against it. And hopefully I'd raise her in the way that she doesn't feel pressure or need.''