I often start dreading something I have to do and I'll feel crappy because I'm dragging my heels, making myself do what I need to, but it takes so much motivation I stop often for breaks and feel crappy because I'm being so unproductive on the whole. Things are just so much easier if you can want whatever is coming next so that you are pulling forward instead of being pulled forward. I'm not sure what that involves exactly. I came home today hating work and feeling joyless about what is coming up. If I can make a plan, or something that is my own expression and execute that, then I think it won't feel like I'm being made to do all of this. I have to find a way to make what I'm doing my own. I have to find a way to affect things. I have to leave a mark on it. I get feeling down because sometimes what I work toward reaches a dead-end, snubbed by someone else's plan which is found to be better. I lose motivation when that happens, even though it just means I learned something new, which is a good thing in the end. I'll have more opportunities though, so I just need to try again.
One thing that might help if you're in a similar situation is to focus on something small and concentrate your effort there. If you can accomplish something there, it is a good feeling, and there is more chance of that if you don't scatter yourself over many different tasks. It's easy to scatter yourself, or it is for me if there's nothing in particular I want to do, so it just takes some decision to concentrate on something and dig into it. Anything like that takes some time investment before you can even really begin, but maybe if you can focus on a particular goal it's easier to, for example, read up on what you have to so it is fresh in your memory, or for example, collect all the materials and tools you need to do something. Because if it's something small then you don't feel overwhelmed by so many larger tasks you try to attack all at once and produce little affect on at that level. Go small. There is one small thing you can accomplish with focus and start there, ignoring the bigger picture for awhile.