Make a to-do list every day of everything you need to do (e.g. shopping, cooking, cleaning etc.). Try to be as detailed as possible to prevent cheating. Your day is not done until everything on your list is complete (if it's not done, then there has to be a really good reason and not "I'm too tired"). It's a great way to push through lethargy and organise your day (and feel proud of yourself for making it through the list). Don't forget to put your workout on your list.
I find this a great mood booster and a great way to keep going. I am terrible for putting off tomorrow what i can do today, but if it's on the list it has to be done. I also feel pretty good about myself for finishing something that I started and give myself little rewards to keep it interesting