I travel quite a bit and sometimes cannot always log in my few writers hours to keep a story warm. The best thing I've found is to print out the outline and notes and read them as you go--if you can't get to a computer. Of course, those people who are still handwriting, and there are a lot of them, can use their tablets.
Those notes are so important, to keep that story warm inside you and keeping that direction of the story and flow and pulse inside the writing part of you, no matter whatever you are doing.
Once cold, a story is difficult to pickup and run. I'm writing something now that is very fast and a few days away from it was a disaster, so far as momentum.
I am about to step back into the story, this after losing chapter seven, a lead chapter for a suspense. I had to jump into eight and will have to edit when finding seven. this is unusual for me, as I save constantly. But I've been changing machines and things disappear--it was a great active chapter, too. I think I can find it. Maybe.