Carl Jensen is a radical saver in Longmont. At age 43, he's now retired.

Courtesy of Carl Jensen

Imagine this: You're in your 30s or 40s. You're worth a million dollars. You've just retired.

It sounds like a dream, but for people called radical savers, it's a reality. Radical savers are part of a movement called FIRE—Financial Independence/Retire Early—and they put about 70 percent of what they earn into a retirement fund.

Carl Jensen, a radical saver from Longmont, talked to Colorado Matters about how he was able to retire in his early 40s. Jensen said he's always been a pretty big saver, but preparing himself, his wife and their two daughters for a new level of frugality took extra steps.

Not everyone is in favor of radical saving. Nicole Strbich, a financial planner with Buckingham Financial, cautioned that early retirees can disrupt the social security system, and may find themselves broke at 75 if plans go awry.