You kind of know what you love to talk about, research, and explore. But when you start blogging every single day, you see the same themes come up again and again.
For me it's parenting and childbirth, personal finances, writing/blogging/podcasting, a little bit of government/current events, business and entrepreneurship, travel, college/education, whatever somewhat unique experiences I think I have had, nutrition, and the occasional movie review.
If I continue blogging, my interests will likely change and I will certainly have more experiences to write about. My blog will become like a time capsule to remind me of what I was interested in at a given time, what I was watching, what I was reading, what I was learning, and what I was experiencing.