What would be the process of creating a blog about motivation? Do I buy domain and connect it to wordpress? How can I organically grow it?
You can get all the information on google.
But just for a start, you can buy a domain name which is relevant to your niche, buy a web hosting, connect that domain to your web hosting, install WordPress.
Buy a web hosting preferably with Cpanel.
Then you will need yo design your blog according to your niche, you can take inspiration from other website in your niche.
YouTube will also help you design your website.
There are in depth tutorial available on how to build a website.
Next step will be putting content on your website.
But before you go ahead and put any content on your website, i highly recommend you learn basic SEO.
You can learn the basics from Ahrefs' YouTube channel.
After that you will start to get a clear picture of where you need to go next.