“I don’t feel like I’m qualified to write anything worthwhile”
I stopped writing a few weeks ago because I felt like I had run out of things that I was qualified to write about (which was a small pool to begin with). It’s scary giving people advice or sharing your thoughts when you don’t have much to back it up. It can feel like you’re just making things up, or like what you have to say isn’t really important.
And this is true in some scenarios. If you’re writing about nuclear fusion and you don’t know introductory physics, then you have a lot to study before you’re able to write something useful.
But you don’t need a PhD in anything to talk about life. If you’re writing about something you have an opinion on, or something that you’ve learned from your own experiences, then that’s definitely valid. At the very least, what you have to say applies to you. And since you aren’t that much different from other people, there’s probably someone who will relate to what you have to say. So say it.
“It’s already been written”
It hasn’t been written by you. It hasn’t been written from your unique perspective. It hasn’t been written in your style. And that makes a difference. Your perspective might be the one that someone else relates to the most.
“No one cares about this topic”
You care about it, so someone else probably does.
“Almost no one’s going to read it, so what’s the point?”
You’re not going to be famous, but you might help one or two people. If even one person finds it useful, then that’s worth it, because one person matters a lot. You know the impact that the things you’ve read have had on your life. Having that impact on even one other person seems worth it to me.