The easiest thing to do is to run ads on the pages of these posts. Traffic needs to be good, of course. You can work through the same RNS.
You can try paid access to content, but how much you get to earn, as in the first case, is not very clear, you need to study.
Articles can be sold through copywriting exchanges. Maybe even better will work. Medical topics are quite popular and money, as for psychology, I do not remember, but also nearby.