Anxiety and depression in general might be too broad to rank for easily. There are a lot of products and a lot of angles to take to approaching the niche. Your content will resonate more if you narrow down the target audience a bit.

Neurosis might actually be a better option because it is narrower. You can point people towards CBD as an option. There are a ton of CBD affiliate options. You can talk about your opinions about the techniques in specific self-help books (and link). You can write about common techniques for management and potentially review/link to related products.

Really, you could do all of those things for anxiety and/or depression too. It's just a matter of figuring out what you're most comfortable creating a lot of content about. And finding the right angle of approach so that you relate well to your target audience.

ClickBank has products in this niche, but you will have to do due diligence to check if they are any good.

Also make sure your site has a medical disclaimer.