Can you teach yourself positivity?

[randomer]

I don't know. There are gratitiude journals and all sorts of paraphenalia which promise to help move our mindsets towards being positive.
Do they work? Does anything work?

Stoic philosophy is good, and doesn't deny that life can be tough, but enables you to develop a more positive perspective on things.

Have you read Learned Optimism: How to Change Your Mind and Your Life, by Martin E. P Seligman?

It's ages since I read it, but I found it useful, and to this day I'm more likely to view my glass as half full.

I'd say yes. It's a discipline. The daily gratitudes idea is good. Once you start, it becomes easier the more you do it. Look for silver linings.

There's a saying, something like 'what if tomorrow you only had what you said thank you for, today?'.