Have you tried altering your diet? Eating healthier can help on occasion, same with fresh air and sunlight. Depression is a struggle, and it feels like a hopeless unending battle, which is exhausting and kills motivation. I can't speak for medications as I've never been brave enough to seek that level of help, but one trick that helps me personally is changing the verbiage I use. I do not consider myself a motivated person, but I do strive to be disciplined and a good person. With that knowledge of myself, I will use the word discipline to push myself to keep moving and doing things. I may not feel motivated or desire to get out of bed, but I'm disciplined enough to do it anyway. I'm not trying to say it's easy or simple, but offer a trick I learned that works for me.