I also think you can alter your thoughts about your procrastination/need for change/perfectionism/laziness a bit yourself if you work through it.
I do make sure I give up beating myself up after a while otherwise it becomes counterproductive. In fact, giving in to indulging myself - but accepting that this is what I'm doing - is the way I kick start my motivation. but it has taken me years to learn that this works for me. So I simply say - yes, I'm exhausted, yes I've taken on too much, yes, EVERYTHING is a tip. So I'll do ONE thing, but after I have allowed myself to slob/rest/do nothing etc.
The problem as others have said is not doing anything well, including your downtime. So you sit with the kids worrying about work, worry about kids when working, sit on your arse on MN but think you should be doing something else. So let's all allow ourselves to sit on our arses, but recognise at some point that has to stop.
For instance today I am marking at home and working on some revisions to a paper. I use MN as a motivational resource: bit of work, quick post, bit more work, quick post. I think I get more done this way than staring blankly at work worrying about it (or not doing it). But it helps to structure things a bit - so I use the old writers' trick of leaving a sentence (or a piece of work) half finished, so you have something to immediately go back to. I have started doing this with laundry (which is contrary to what all the anal retentives do 'No! You MUST put it all away immediately or you will die!'...) I know that I will do it if I start the job, distract myself purposefully, knowing I've got to finish it, and then go back. So I do a BIT of editing, or half write a paragraph. MN. Then a bit more. I mark two essays. MN. etc. With laundry I force myself to at least sort it into piles per person, to be put away next.
Sometimes, though - if I chip away at myself like this when demotivated - I surprise myself when the 'flow' comes, and I can work solidly, non-stop, for hours and hours, completely focused and driven. Even on housework.
I suppose - being in a 'thinking' and 'writing' profession, I have had to accept that this is just how I work and wild horses are not going to drag me away from it. I am much better when nibbling at things. It's the avoidance of them that is hardest though and when I know I'm really avoiding something, that's when I have to slap myself into action. Doesn't always work but I'm getting better at it.
What I do need to work on much more now is saying NO to things and planning contingency time. Rubbish at this.