I'm in the middle of reading "Man's Search for Meaning" by Viktor Frankl. It was a book recommendation from my engineering manager and oh wow, it is an incredible book!

One of the things that stood out the most out for me and IMHO relevant to your question is that happiness or optimism can't be forced or willed, one needs to find what to be happy about or optimistic about. It's just like laughter, you can't make somebody laugh, you need to give them something to laugh about, i.e. a joke.

He also talks about optimism, which comes from the Latin optimum, conveying the idea that optimism is not some kind of always-happy-go-lucky kind of attitude, but is more akin to an ownership attitude towards whatever the present circumstance and choosing the best for that situation, the optimum.

I also have a deeply seated cynicism together with the idea that humans are ultimately going to be their own undoing, but that doesn't really stops me from being optimistic about my plans, trying to make whatever influence I might have to make the world/workplace/home a better place, and I can rejoice together with those that I see doing the same, in whatever way.

I can't recommend "Man's Search for Meaning" enough, it has really helped me to articulate that hope/optimism I wanted to posses in the mist of... well, everything that is going on!

Best of luck on your search!