For me it has always been me talking to myself. Very rarely I would take an approach where I needed to detach from myself in hopes of finding the best option objectively and without my own bias etc.
To start off, try to speak to yourself just as you would with any other person. Obviously, you may think that you know yourself well enough (I'll explain why this is wrong later, but for the sake of explanation just go with it) so that you can try to speak to yourself like this is your best friend. You know your likes, dislikes, things you like to talk about, things you are afraid of. The best feeling you can seek is to be able to speak with absolute freedom, because it's you yourself you are talking to. So, you don't have to fear of coming out as being awkward.
I was all over the place when I started. Sometimes I still am. But it's quiet unlike speaking to some other person. When you speak to others your mind starts to wonder what if they think you are too weird. You absolutely will be weird in the start, just like you are weird around new people. But as your friendship grows you get more comfortable.
So, the key is to keep writing on the regular. I normally write a couple of pages once a month. Lately I've been writing more due to some stress in my life. You can write once a month, or once a week or a day. Or even multiple times a day, but make it a habit to write regularly. You will find that very quickly you will become comfortable with this new friend and your writing style will change. Mine has changed multiple times over the years. It has taken me on a journey of self-discovery. And I promise you, if you can go even 10% as far as I have in journaling, you will recognize that you never really knew yourself before you started journaling.
Oh, I have a story that is not much different. I am what you called science-minded person. So, you can imagine what I must be thinking about tarot cards or astrology. But I definitely do get you. Few days back I had a dream. That lead me down the rabbit hole of deciphering its meaning. It wasn't anything spectacular, just plain old random-ass dream. But dreams are pretty big in my society so there is ample material to decipher them. I picked one up at random and found out that my dream was good. That was it.
I admit that some other dream dictionary might tell me that my dream is an omen of doom, but just like yourself I took that initial meaning and wrapped it around my situation well enough that I could spend next few days in relative calm. Even though I do not believe in them at all.