Oh yeah, I know exactly that feeling of being tired and having no energy. I've learnt that I have to have a very specific focus or a reason to keep on going otherwise pointlessness just overwhelms me. For instance, right now I am studying for a music grade and that gives me energy each day because I'd really like to pass, you know? I also make sure I have 1 or 2 nights a week that are special (for me, I have a take out meal and a couple of beers!) so that I have something to look forward to.
Having something to work towards and something to look forward to. Those 2 things together work for me.
Lots of love to you