I feel your frustration and can relate to it. I actually have a bit of a rep when it comes to not sticking to things, not being impressively self disciplined. While having a job, it's my boss who dictates part of my routine in life - my time, my duties or actions and so on, for a period of the week. Technically, she's one of my disciplinarians in life.
Self discipline is definitely a tough one. Self discipline means we're the boss (of our self). For me, what helps at times involves me asking 'Who's in charge?'. If 'The go get 'em Commander of solid direction' aspect of self is in charge, not a problem. I can stick to just about anything. If 'The Wonderer' in me is in charge, you can bet there are going to be problems. If you trigger the Wonderer in me, to wonder about anything even remotely fascinating, bamm, I'm in. The house can remain an incredible mess while I'm researching stuff on my laptop or wondering about what new additions are on Netflix or wondering about what there is to do outside the house. If you keep me wondering all day or all week, the house will stay a mess for that day or that week. I just love wondering and researching. It's a bit of an addiction :)
If you trigger 'The Visionary' in me, it's kind of the same story. Using the messy house scenario again, once I'm in my imagination I can easily see the kind of house I'd actually love to live in. I can see a lap pool, a home gym, split level flooring, incredibly colourful walls and so on. It can get to the point where I don't even want to clean the house I'm in because, basically, I'd much prefer to clean the one I imagine :) So, there goes my housework routine out the window.
Now, after all this, that Commander aspect of self (the one that keeps us on track) might chime in. If I had to sum it up, I'd say it sounds a little like 'What are you doing?! You're bloody hopeless. Get it together. You're a loser; you're losing time, momentum, direction, self-discipline...'. While the Commander is harsh and sometimes a little depressing, this aspect of self remains incredibly important. I believe it's the Commander who demands the need for a solid plan, a need for focus/refocus and routine as well. At the same time, I believe it's important to listen to 'The sage' in us who might be saying 'This is tough, be kind to yourself in the process of reformation. Reforming your self is an art, it requires skill and sometimes a lot of practice'. Can be tough to channel the Sage at times :)