Is it possible to genuinely 'choose' your happiness, or do circumstances dictate it?

Hey fellow optimists! I've been thinking about this a lot lately and I'd love to hear your perspectives. As someone who's always tried to approach life with a positive attitude, I often wonder if my happiness is truly under my control. Can I genuinely 'choose' to be happy, or are there underlying circumstances that dictate my mood? For example, let's say I'm going through a tough breakup - can I just will myself to feel happy and move on, or does the pain of the breakup itself play a role in how I feel?

I've read some books that suggest we have more control over our happiness than we think, but at the same time, I've also seen people who are struggling with mental health issues or traumatic experiences who still manage to find joy in life. It's like there's this invisible line between what we can and can't control.

So, fellow optimists - has anyone else ever grappled with this question? How do you think we balance our desire for happiness with the reality of circumstances beyond our control?