I have that feeling of just contentment sometimes, what I do when I feel this way is think about what I am providing for others. Me being happy also makes my Fiancé happy, my viewers happy, and my family happy. So when I realize who else my state on contentment effects it makes me look into what the problem is and solve it quickly so that others around me can feel better too.

Apathetic contentment? Nothing good or bad happening, no real positive or negative feelings, just doing fine and going along with life.

Every human being has those phases in which they seem to feel empty, numb, apathic, not being able to start doing things, not feeling like anything. This could be caused by stress, hormonal changes, depression (and a whole mountain of disorders and other more harmless causes) but as you didn't give that much information about your current situation that's a pretty impossible thing to determine. PLEASE don't go around thinking you suffer from some mental disorder. Normally this feeling should go away within a few days/weeks. If this feeling lasts for longer than a couple of months or it seems to be getting worse and worse by the day i'd suggest seeking help from a councelor or another professional. It's better to prevent than to cure!
I hope this helped!

I've felt that. It's eh.

I can't say that I have ever felt like that, so I don't have any personal experience to help you with that. And I hope you find something or someone to help you through it.

Side note: I finally know where your profile picture is from.