Good question, Agnes. I recognize that just because one finds one's own work interesting doesn't mean that other people will necessarily find it interesting. Since writing is supposed to be about communication, this might present a problem. What to do about that, Agnes!
My answer emerges from what I call Ben's First Law of the Internet, which can be expressed simply as: You aren't the only one. I coined the First Law back around 2000, when a pair of simple Yahoo! searches--this is well before Google figured out search, remember--quickly led me to (1) a website that had the complete rules to an obscure chess variant I'd been discussing with a friend, and (2) a website devoted to cataloging the cosmetic differences between different model years of a specific model of guitar that I happened to own. Which was to discover: not only were there people out there who shared my interests in some fairly obscure subjects, but some of those people were sufficiently interested to take the time to make websites about them. (Please keep in mind, this is back when people still coded websites by hand.)
I doubt that kind of thing exists anymore in exactly that form--on the more mature Web, those obsessives' websites have now probably been replaced by Pages on Facebook, but the principle remains: You aren't the only one. Someone out there shares your interests.
So I just write about what's interesting to me, and figure someone out there might care.
I also freely admit that "what's interesting to me" is evolving day by day as I keep up this practice. And hope that maybe, just maybe, the experience of that evolution might be interesting to others as well.