But his top money saving tip has nothing to do with ditching credit cards , downsizing or tracking expenses . Rather, he advises finding someone to hold you accountable for whatever financial goal you're trying to achieve.

"Our mantra became, Sacrifice now in order to be able to win later ," Cahill tells CNBC.

David Cahill and his wife Meg managed to eliminate $18,000 worth of student loans in 54 days , thanks mostly to extreme saving.

As soon as he and his wife committed to paying off their loans aggressively, "we actually sat down with our friends and told them about the ambitious plans that we had and asked them to provide us accountability," Cahill says.

It was the smartest move they made during their debt repayment journey, he says: "The support that we got from them — the texts and phone calls of encouragement — really made a difficult experience for us that much more gratifying."

Plus, getting their friends on board right away made it easier to decline social activities that came with a price tag. "They were really supportive and understood that we couldn't go out for drinks or go bowling on a Friday night," Cahill says.

It made a huge difference for the couple since, Cahill admits, before buckling down, "we were going out to restaurants and drinks with friends far more often than was practical."

A few small changes here and there, such as asking someone to provide accountability, can make a big difference. Ultimately, "there's nothing special about our story or about us," Cahill says. "With the appropriate mindset and willingness to adopt the correct strategies, anybody can replicate what we did."

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