I guess it means diffrent things to diffrent people.
the way I look at it is

have I had a good day, is their anything bothering me or making me anxious?. am I suicidal. have I actually accomplished anything today, am I currently where I want to be, etc.

but it's diffrent for others

say: someone's dog goes missing, and then later that person finds it

then that person might be okay simply for having the dog back. it might not necessarily have anything to do with how the rest of their day is going