A healthy 29-year-old woman shocked Reddit users after revealing her stage 3 colon cancer diagnosis—despite no genetic risks and an active lifestyle. “I ran a PR half marathon last year and work out 3–4 times a week,” she wrote.

She began noticing dark blood and mucus in her stool, thinner bowel movements, and more frequent trips to the bathroom. “I saw my PCP in January, but then delayed the colonoscopy because my symptoms got better,” she explained. When she finally had it in April, doctors found a tumor.

“IBS, ulcerative colitis, celiac, and Crohn’s all have similar symptoms to colon cancer and are extremely treatable,” she added. “It’s better to know what’s going on in your body.”