Even as John Bourbeau and his wife's combined income climbed to more than $250,000 a year, they stayed in the three-bedroom house they bought nearly two decades ago.

That's kept their monthly mortgage payments at an affordable $1,325 a month, leaving them plenty of extra cash to max out their annual contributions ($23,000 each this year) to the Thrift Savings Plan, a 401(k)-like plan for federal workers.

As a result, Bourbeau now has $1.1 million in retirement savings in his individual account. That's in addition to his wife's savings and the pensions they will both receive.

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"You can't live just for today. You've got to think about the future," he said. "You want to be in a position to enjoy it."

Still, he said they try not to be excessively frugal and enjoy spending money on things like vacations and concert tickets, like a recent trip to Canada to see a Def Leppard concert.

"You don't have to deprive yourself of everything," he said. "Experiences are worth it."