When I proposed to my girlfriend, Sarah, in September 2013, I thought that would be the biggest moment of my year. Little did I know that just a few months later, at the age of 24, I would be diagnosed with stage III colorectal cancer.

My diagnosis came after I’d started to notice a pain in my back. I thought it was just kidney stones, but doctors found a mass in my abdomen during a wellness exam. An ultrasound and a CT scan revealed...