I'm recovering from being laid up with a minor injury (badly sprained ankle, stiffness and tissue damage) and some problem areas in my muscles, joints and tendons. I find mentally adjusting to this kind of thing to be worse than the physical injury. I've gotten up to basic yoga, situps, pushups, squats and walking again, while seeing how I feel after a jog sometimes.
I have had a healthy diet and lifestyle for several years so I've just started to get a little soft and put on maybe 10 pounds from the inactvity. I was very slim before.
Any tips on adjusting to more low-energy workouts and how to move things up without making anything worse?
For me, it was more about just getting myself to the gym and not burning out. You make baby steps as in, don't push yourself to max out of the gate. So that translated into picking weights that I could lift without a lot of strain, walking the treadmill and occasionally jogging, taking long enough breaks between where I would feel energized enough to do another set.
I did this until simply going to the gym became a habit and routine, so I didn't feel like I was going out of my way or missing out on other things. The good news is you adapt very quickly so if you really decide to start pushing yourself a bit more after that, it won't be as painful as had you jumped directly into a strenuous routine. If you're already eating healthy, you should be bouncing back from workouts just fine provided it's including enough protein for what you're lifting.
The most important thing is making it a habit and once you're at the gym, you can decide for yourself how much you feel like pushing yourself. I wouldn't worry too much about results this early on, either, as you're wanting to make it a habit that doesn't burn you out. You'll eventually see changes as you track your progress and learn how your body is responding.
