Depressed and Not Depressed

Yesterday, I was depressed. Today, after a decent night's sleep and no alcohol last night, a positive outlook. I knew that today is going to be a long one, so I planned this. Day of work followed by an evening of doing therapy at the DC campus of an out of state university.
My mood. When I'm depressed, everything is so bleak, so unchangeable. Today, though, relatively positive. What would it be like if I felt like this all the time. What could I accomplish? What could I be?
And, listening to music today. "When It Comes To Love" by Fleetwood Mac. From the non-Lindsey phase and, love Lindsey like I do, a great, hooky song. I'd love to hear Lindsey do a version of it himself.
Even my digressions are positive today.
Should I consider medication? I couldn't take, though, an effect on my sexual drive. I've just recovered a good sex life. And I LIKE it. Alcohol? I've reduced my drinking pretty mightily.
And is it depression, anxiety, a personality disorder in me. All of the above maybe? Let me leave it for today. For now, at least, I'd like to bask in the positives of today's mood...