Ananda, when I'm resisting sitting meditation, I substitute for this:
https://www.youtube.com/watch?v=_pYoDdUijY8 (mostly stretching)
or this:
https://www.youtube.com/watch?v=PElmyy_kwN0 (a little more strengthening)
or this:
https://www.youtube.com/watch?v=D8oKWQiEWYs (body scan lying still)
These are nice ways to provide structure to practice, and to get back in the body while practicing self acceptance and body acceptance. I found all three of these extremely helpful when I was in a lot of physical pain, or I was feeling too rigid or driven or just not wanting to sit, and I still rotate through them on a fairly regular basis.
You'll get through this lull. One hazard of having a plan is that we can be highly self-critical when we don't follow it to a T. It's important for me to be aware when I'm in a flow or when I'm feeling excessively driven or when I'm feeling like I'm failing myself. It's okay to back off a little. If you were doing a half hour sitting practice, maybe back off to 15 or 20 minutes for a while, or try something related but different, particularly adding movement. When I feel stuck I like to remind myself I need to wiggle out, and wiggling means moving. And moving is one of the main antidotes to a depressed state.
You might also consider deep, circular breathing techniques, but I wouldn't dive in completely at first. I started with 25 breaths, then when I got used to that, 50, then 100. There are different methods, but I was taught to blow up an imaginary balloon, breathing through the nose deep into the belly, and blowing out of pursed lips like I'm filling a balloon. It works the core a bit, and sometimes my face cramps, but it is an enlivening practice. Some take it further and into holotropic or shamanic breathwork, though I haven't ventured into that realm as of yet. Circular breathing of this kind is cleansing and invigorating if nothing else. Just a little something I've added to my meditation/yoga practice...
Best wishes...