The trigger for me was blood in my stool. It was the slightest amount but I pursued it because that didn’t seem right. Turns out I had hemorrhoids which brought up something I feel hits others - I was embarrassed.
Fortunately the doctor that performed a banding procedure pushed me to get a colonoscopy purely out of being through and seeing the number of incidences increase at my age range.
I often wonder how much the embarrassment factor comes into play here.