Creating and selling courses on your blog can be a successful way to make money online. The course itself should be relevant to your blog, and based on a topic that will benefit your audience. Although it may take time to create the course in the first instance, once completed, you can then repeatedly make money from the course each time you sell it.
How much will you make? I think my best month with Google AdSense was almost $5,000 over the last ten years. That amazing month blew my mind since it was actually near the beginning of my blogging journey. When you go from making zero to $5,000 in a month, that will rock your world. For me, it also got me even more excited because I knew there were other ways to monetize.