I quit my job, went back to school, and started a new career in my 40s. I learned 3 lessons about starting again.

Kate Portillo went back to school in her forties.

Courtesy of Kate Portillo

• Kate Portillo ended her 13-year career in retail to go to school.
• She retrained as an urban planner, but found it challenging to establish credibility in a new field.
• Portillo's advice for anyone making a midlife career pivot include finding a mentor.

This as-told-to essay is based on a conversation with Kate Portillo, 51, an urban planner who lives in Chicago. Her employment and education have been verified by Business Insider.