I’m all over the place, much like Ant has said.
( I am a little less worried about me now that I know I’m in good company) 
but anyway, I can only offer this one piece of advice which I try to follow strictly, but like everything else in my life, is also all over the place.
but my advice is to get up and exercise every couple of hours doing anything “off your ass”.
if my theory is correct and our metabolisms are respondent to what the body “thinks it needs” rather than to what is actually used; then it stands to reason that if you were to say, …. get up and run for 10 min,… that your metabolism will respond as such for I’d guess about the next 2 – 3 hours.
so in other words, as long as you were fooling your body into thinking you were exercising all day, it would in time respond with a metabolism that you’d find on someone that really does get exercise all day long.
and even if my theory is completely wrong, its still a good excuse for getting up every couple of hours and blowing the dust out of the machine.
I think it does get more oxygen to your brain = better production of the time spent actually working.