Have you ever ignored a symptom that later turned out to be serious?

Though not cancer related, I had a very dramatic weight-loss in late summer, early fall of 2023. I was losing weight pretty fast, drinking lots of water, working out. I didn't really realize I had lost a lot of weight, but did notice my clothes were fitting better. I was just letting myself enjoy the weight loss and the hydration. During a visit to my favorite place to suspend reality (Disneyworld), I was feeling excessively tired. I thought it was just all of the walking, but this was beyond the tired I had ever felt before at Disney. I was having to take very frequent bathroom breaks. It really interfered with my vacation.
I came back with terrible gastrointestinal and other issues and had to make a doctor's appointment before going back to work. I found out I had Type 2 diabetes- certainly not made any better by all of the "treats" I had at Disney. I then went to the opposite extreme- severely restricting my diet and always keeping my numbers as close to the low end of the acceptable range as possible, and not worrying much about if I fell below because "lower is better" right? Not so much.
I didn't understand why I had such terrible brain fog and my memory was crap. I thought I was getting early onset dementia. I was almost hysterical and went to my PCM. When she saw my glucose monitoring numbers, she set me up with the nutritionist to get me on track and to teach me about balancing my nutrition.
I DO have a diabetic cataract on my right eye that I need to have removed, and that will be happening soon.
Please, do NOT ignore symptoms.
I had no "symptoms" that would have led me to be concerned about my cancer diagnosis. Though I had not gone for mammograms for several years before my diagnosis because I was "busy" or I forgot, there was no lump to feel, no fatigue, nothing that would have made me wonder. Looking back though, I had a discussion with a friend of mine who had just started working for a non-profit hospice organization. After that discussion, I had several dreams that I was diagnosed but I kept doing self-exams and "no lumps" so I didn't make much of the premonition.