It might not be laziness, but addiction and please don't get me wrong here. Depression, anxiety are caused by drugs in the brain, and much like any other drug, you can get used to it, and sometimes needing it.
Which makes people who really want to get better in a bit of a bind. But what makes you happy, and things that excite you or gets your adrenaline going, these things can help you.
Exercise, physical activities or just likes that truly make you happy, even if your lonely/sad it can help you get out of those ruts. I realized when I did yoga, swimming and bike riding I felt much better not cured, but happier/clearer, when I stopped and did a lot of nothing i got lazy and depression got worse.
The hardest part is not letting your depression, bad moods, loss of energy hold you back from doing things.
Your right about it though your body doesn't want it but your mind also keeps you from wanting to get rid of it, I still suffer from the same problem, but I do my best to remain positive and keep the mind and the body active.