There's two elements of writing. One is fun when it's going well, and miserable when it's not. The other is never fun.
(1) Thinking, planning, brainstorming, daydreaming, and otherwise figuring out ideas.
(2) Communicating those ideas using words, language, and structure.
The first part of writing is thinking - figuring out what you want to say.
This is incredibly enjoyable and fulfilling when you work out an interesting idea on the page. Sometimes you've almost got something, but not quite, and that can be frustrating.
The second part is the mechanics. Above, I said this is never fun, but that's probably not true. Occasionally it's fun in a craftsmanship sort of way. But usually it isn't. That's because the thinking, planning, daydreaming, and brainstorming you do is hard to capture just right on the page, and that's a yucky feeling.
"I've got this idea, I think it's a good idea... but the words I've written fail to communicate it."
The first part of writing is the most important part. Without it, the second part doesn't matter. This is an essay assigned in high school where there's only one or two correct topics that have already been well-worn. You don't get to actually think through interesting ideas - it's just an exercise in mechanics.
That's why high school essays feel like torture. I think this dissuades a lot of people who could be good writers. Anyone who can think clearly and then communicate those clear thoughts could do some good writing. But high school assignments tend to make people think that writing is about the mechanics, rather than the thinking and brainstorming and daydreaming and synergizing and synthesizing ideas.
Certainly, the mechanics of writing can really elevate a piece and make it shine. The final bit of polish and finish can make the difference between "good" and "masterpiece."
What's blogging? Blogging is just a publishing platform for writing and other forms of media. There happens to be almost no cost to doing it, so the stakes are low. Thus, you're allowed to do step 1 (the fun thinking part) without necessarily doing step 2 (the not-fun mechanics part).
That's why blogging tends to be a lot more fun than high school essay writing. On most blogs, it's practically the opposite - it tends towards rambling, unedited, and otherwise mechanically unsound form... but the blog author gets the enjoyment of thinking on page, and people who stick around get exposure to their thinking.
The not-fun mechanics part is what elevates a piece of writing from good to masterpiece. My strategy is roughly to do a lot of step 1, which I enjoy and which doesn't tire me out. On the rare occasion that I think a piece could really shine, I'll apply the polish and mechanics in detail (which I don't really enjoy and which does tire me out) for the chance that it becomes something lasting.
I'd recommend something similar if you're just starting. Enjoying the process is big. Certainly, study the mechanics and gradually improve yours. But don't obsess over them. Without interesting thinking at its base, mechanical communication means nothing.
Learn the mechanics! They're useful, yes. Necessary sometimes, too. But it's not the core of writing. Writing starts with thinking. The mechanics are there to serve you in communicating your thoughts.