Maybe reframe "nothing to do" with "I can do anything I want to do today". I realize depression can be a fucking bitch and sometimes it's not that simple. But for me, when I'm there I use a 3 step mental process.

1 - Think of something simple you can do that would improve your mental well-being. Cleaning up a little, knocking out something you've been putting off, etc.

2 - Just start. Work on #1 for a minimum of 15 minutes. Set a timer if you need to. More times than not, momentum will take over and 2 hrs later you just got a bunch of shit done.

3 - Take a moment to appreciate how precious time actually is. The wealthiest person on the planet can't buy more of it on their deathbed (to certain extents). It's the most valuable resource on the planet. Make the most of it.