When I began running at age 17, I ran about three times a week because it made me feel good and helped me maintain a healthy weight. It soon became a routine and a healthy hobby that helped me manage stress and anxiety and, best of all, socialize with other runners.

After I’d been running for about a year, I was diagnosed with ocular melanoma, a very rare eye cancer. The cancer, thankfully, was only in my optic nerve and hadn’t...