Second, have you spent the last year working so hard that nothing short of a physical illness will make you slow down? Do you regularly push through problems with sheer willpower? Do you crave the next "green" unit test result beyond all sanity?
If so, you're almost certainly burnt out. Don't try to push through it. Take a vacation. Get outside. Allow yourself to be distracted by a pointless and amusing hobby for a month. You can't fix burnout with willpower. You need to take time off and refresh.
If you haven't been mistreating your body, and you haven't been pushing yourself too hard for too long, then it's possible you're lazy, or depressed, or something else. If you think you might be lazy, commit to making some useful progress every morning for 30 days, no exceptions. Or try a Pomodoro timer. These might be enough to tip you over the edge and get you moving. But don't do this until you've ruled out burnout, because it will only dig you in deeper.