I struggle with accomplishing everything on my to do list, and often a task will sit on my to do for longer than necessary. What can I do?

I think you should just sit and think for some minutes what is stopping you from fulfillment your goal. Just dont think that you have a lot to do, because you are not going to make anything done. Just focuse on one and try to make it done, step by step. A little, even if it is not a lot, you realised, at the end of the day , that you will make it happends. Be positive! It will help you a lot. And this aswer is from a negative person, just like you, i guess.