We all have times, whether a day or more, that we feel this way. I find that if I reflect on my success I am more likely to stay motivated. I am doing this for myself not for anyone else. I have 4 dogs that look forward to walking with me. I also have human work out buddies, though they cancel on me sometimes (my dogs never do.) I also know that I feel better when I eat right and work out than when I sit and veg all day.
My hope for you is that you find the motivation you need. Until that time maybe you can fake it until you make it.