Things you thought were mundane and pointless, but (as it turned out) most certainly weren't

Sorry, drawing a blank for colorful opening illustrative example this time, but basically would include anything you found, or happened to you, or whatever, which at the time seemed of minor import but which later most certainly turned out to be hugely significant.

I developed a massive sweet tooth around January of 2008. All of a sudden, I had to have candy around all the time. I’d always liked sweets, but never to the point where I would crave them every day. Kinda weird, but I wasn’t gaining weight or anything so I didn’t think much of it.

6 months later, I’m diagnosed with diabetes. As soon as I get my blood glucose under control, suddenly my need to eat candy all the time goes away.

I never had any of the normal symptoms - peeing all the time, thirsty, etc - but man oh man did I binge on candy for about 6 months. It was fun, 'til I found out why!

Is that what you were looking for?