I'm an 83-year-old doctor who still works 50-hour weeks. I never give any thought to retirement — I still have things to contribute.

• Dr. Joseph Maroon is a neurosurgeon, professor, and triathlete.
• He stepped back from performing surgeries five years ago, but still works up to 50 hours a week.
• He said work keeps him engaged and allows him to use his brain.

This as-told-to essay is based on a transcribed conversation with Dr. Joseph Maroon, an 83-year-old neurosurgeon living in Pittsburgh, about his decision to keep working at his age instead of retiring. The following has been edited for length and clarity.

At 83, I'm having more fun now doing what I do than I have in the past.