At 25, he decided he didn't want to be stuck in a job forever. Here's how he was able to retire by 36.

• Yaron Goldstein achieved financial independence at the age of 36.
• Goldstein's strategy included mindful spending and investing a big portion of his income.
• He follows the 4% rule, which is common in the FIRE community.

Yaron Goldstein was 25 when he decided to start working toward financial independence.

Goldstein was working toward a Ph.D. in computational and advanced mathematics in Berlin, his hometown. While on a research internship in New York City in 2010, he connected with a Wall Street investment advisor who would become his unofficial mentor.

His mentor gave him a list of what he considered "required reading." The list included Tim Ferriss' "4 Hour Workweek" and Malcolm Gladwell's "Outliers.'"