It sounds like depression more than laziness to me. When I got really depressed in college I would do that. Just lay in bed and not move all day. When I moved home, my mom would have to prompt me to do everything like bath, brush my teeth etc.
Now I have more irritability when I'm depressed. I grump at my husband, I grump at my kids, I scream, I cry etc. So I went on cytalopram and it was better. I didn't scream as much. But I still just did the bare minimums.... I bathed, did the dishes, did my work. But all without joy or interest. Then I sat at the computer and wasted time, or hid in my room and read.
One month ago my doctor urged me to try a larger dose of cytalopram. I'm on 40 mg now. It took 2-3 weeks to really feel better. But now I have decided to start losing weight. I started taking my vitamins (B vitamins give you a lot of energy!) Now I'm excercising, I'm smiling more, and I generally feel alive again.
I would recommend getting your meds evaluated! You may be able to feel much better than you do now.
Good luck! And Good job on walking on the treadmill!