I think my best days are my most productive days. I always feel like it’s been a good day if I’ve gotten a lot done.
For example, today was a good day! I ran behavioral trials with my fish till lunch, whilst listening to jaunty tunes. Then I made a delicious cheddar and tomato sandwich. I went back to work and set up 20 new tanks for my second fish population (more jaunty tunes were involved!). For some reason I feel even more productive (and therefore it was a “better day”) if I did manual labor, so the most satisfying bit was filling the tanks using my trusty bucket.