In his 20s and 30s, Craig Wolfe traveled the world, taking on whatever work came his way. In Europe, for example, he opened animation art galleries. And while he was in Fiji, he helped manage a privately-owned island.

But the lifestyle was costly and he had little room to save. In his 40's, he realized he needed to start thinking about his future -- and he has been living a simpler life ever since.

A serial entrepreneur, Wolfe is focusing on his company CelebriDucks, which sells celebrity-themed rubber duckies. And spends his free time on low-cost activities like reading, watching Netflix movies and hanging out with friends.

Watch: The retirement checklist

"I cannot even remember the last time I hit a restaurant or movie or took a vacation," he said. "But I love my home, where I live, what I do. So I never feel deprived."

He's also been putting a big bunch chunk of his savings into a SEP-IRA, a retirement account used by small business owners.

Wolfe said he doesn't plan to retire anytime soon and continues to contribute at least $10,000 each year to his savings.