Describe your goal for categories, as a starting point.

Also answer where you'll define these categories.

You mention YouTube + you might mean content categories on a WordPress site.

If you're referring to a Website, also be sure to state whether you're primarily targeting natural search engine traffic or you're primarily using paid traffic.

Provide more context + likely someone can assist.

You asked your question some time ago but it's still open it seems so here is a pragmatic answer.

I don't know on what CMS your website is built, and I could give you a more precise answer once you have provided a bit more information. Perhaps your site runs on Wordpress?
You could have two "categories" and give the topics that you assign to those categories "tags" such as "anxiety" and "stress".

In php that would look like something like this:

query_posts( 'cat=motivation&tag=stress' );

If that does not mean anything to you, don't worry! I'll help you coding it and translate it into a nice "category chooser" that is afterwards filterable for the visitors of your website.

Feel free to plan a call, really five or ten minutes will be enough to understand your request and propose a pragmatic way forward!

Good luck
Rogier