Can you be positive on your worst day?

I struggle with positivity. Some days I wake up in a positive frame of mind and then the smallest thing can knock me

Nope.
The best I can manage is to bear in mind that the worst will eventually pass away.

yes I know it's all fleeting and ever-changing

Yes. I can acknowledge the good mixed in with the bad.

Yes. I’m not one to be negative for an entire day. I’m usually positive.