Are you in perimenopause? I'm asking because I am and, amongst many other symptoms, lethargy, lack of energy and total lack of motivation are a daily thing for me unfortunately, and has been so for the past couple of years especially.
I recently started on HRT and though I've not found my dose yet I have expectations that it'll help me a lot with that. Mainly because recently I had a few days after starting a new cyclical regime when I felt pretty great and almost like myself again, with lots of energy and motivation. I do take several supplements amongst them magnesium as well but I've been taking them for a long time and to be honest none of them helped with motivation or energy, but everyone's different.
I hope others can chime in and give you more ideas or advice.