That's gotta be time and motivation.
By the time I get home, I feel like comics are a hassle, and I'd rather do something where I don't have to be the one in control of everything. At that point I turn to uncreative means, like watch YouTube, play videogames, or just lump on the couch.
I often feel as though I'm at my best whenever I'm in the zone for creating. It's incredible that I have found the skill to make the things in my head appear on the screen, but other people's creations are just as good, and I want to participate. I love good shows, movies and videogames, and I want to take part in them, but that time takes away from creating. Such is life.