You are so right. And I think it always comes down to this: just be authentic. If you're thinking about "What could I write that blog readers wanna read about?" it's only half the way.
But if you really love what you do, writing about it, telling people about your story, ideas, thoughts, feelings etc, maybe making a bit fun of yourself and don't take things too seriously, that's when people feel that you're authentic and that you're passionate about what you do.

So it's a win-win-situation for both sides. You deliver great value and people are inspired. Or you made my day because you made me laugh with a great and funny post. It doesn't always have to be facts and figures, sometimes a nice story about yourself or something that happened to you is as inspiring as a motivational blog post.

Just be authentic :)