I've struggled with depression since childhood. It'll come back, I'm sure. My father told me to remember that everything is cyclical, and I think that's true. I'm in an up time. There will be down times.
As mentioned by others, it's simply the absence of something bad. Although, I'll go on to say that it does feel good, when you know how it feels to feel terrible at every moment. Not having that is, as someone else said, a relief. Like waking up feeling better after having the flu. Life is just life, but at least that shitty thing is gone.
I've spent half my life feeling awful. And even now, without depression, I'm still painfully aware of how completely fucked everything is. It simply isn't my problem, even though it is. I wish you the best.