I buy an organizer and I write down what I have to do during the day. Every time I finish something, I cross it out in red. I find that this motivates me because anything I don't finish, stays on the list and gets carried over to the next day. It works best when your organizer has more than one day on the page so you can see how retarded and useless you're being.
You can also train yourself using positive reinforcement. It's hard to do somethings, but I won't let myself do what I want to do, unless I finish what I have to do. If you can take your work with you, go to a McDonalds or Timmies and don't leave until you get everything done.
It sounds like you're burning out - you should honestly consider hiring someone. I work months at a time with no days off in between, so I know how taxing it can be to have such long days (yesterday I went between 3 jobs without sleep). Your mind will give out before your body does and it sucks to spend your days off running errands, so I find that thinking about THAT helps me work on things little by little.
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Unrelated, but this is why I don't find "being your own boss" or becoming an entrepreneur all that exciting. I love working, but I wonder whether the stress you have to go through just to call something "your own" is worth it. If the goal is to have enough money to be comfortable, it seems that there are easier ways to do it. The yield might be slightly smaller in the end, but how much are we all really aiming for?
Honestly, I'd work for you 'cause I know you to be a stand up guy, but I'd imagine that you don't have too much to spare since you're getting everything off the ground. If you need an assistant, just give me a call/text me and I'll see if I can find you someone that I can personally vouch for, with whatever you'd be willing to offer in mind.
Also, I'm with firestart when I say get off the booze. Do you really want to be dependant on substances to get things done? It's the reason I bought adderall but didn't end up taking it when I was working full time + in school. You'd be surprised with what the mind can do if it has the right motivation - but the trickiest part is finding that motivation.