Why do I always feel more motivated at the end of the day?

I'm sure someone will try to answer this from a psychology standpoint, and tell me that it's easier to feel motivated when you know you can't act on what you're thinking about, but at this point I'm confident it's not that. It feels like I have higher dopamine levels at night than during the day. Is there a way to shift what feels like a dopamine cycle such that I feel motivated and active during the day, instead?