Things always seem to get worse before they get better

This week was extremely difficult for me. I am always tired, no matter what I do. Sleep seems to be the only thing that I can enjoy lately despite the fact that I still feel tired when I wake up. I also tend to write at night, before I go to bed, to literally get things off my mind. I do this hoping that I will be able to have more restful sleep. It seems to work, I just have to find the actual motivation and energy to write. It takes a lot to be able to sit, focus, capture thoughts and then transfer them into words. I'm still trying to figure out why this week was so extremely difficult for me. It was an all time low. I could've easily laid in bed all week doing abosolutely nothing and would've been happy not talking to anyone. The thing is, there didn't seem to be any appearant external force that would perpetuate my feelings of despair. So where does it come from? I'm trying to figure it out...I think it is a matter of all of accepting the past and accepting things as they are and letting them go. Holding on to them creates stress. But why is it so hard to let go of these things? The memories will be their but the emotions attached to them. How can I continue to grow and progess with such heavy weights holding me down?