I find packing for work trips onerous and unduly stressful.
I think it’s the mental exercise of trying to anticipate the details of the trip (including weather, any free time, etc.) and the associated things to bring, coupled with my unrelenting desire never to check a bag (which is helped by having my One Bag to Rule Them All).
One thing that has helped is a checklist that I consult before international trips. I’ve built it up over the years and included stuff I might otherwise forget (international currency, water bottle, Oyster card, plug adapters) as well as things I need to do (set up international data plan). I don’t always remember to check this list, but every time I do I find a few things I might have forgotten.
My new addition is to do “rough draft packing.” The goal is to decouple the gathering of the things I know I will need from the mental work of making sure I’ve got every last thing.
The idea is borrowed from how I now write blog posts: instead of doing them all in one sitting, now, when an idea hits me, I just sit and write, unedited, to get the bulk of the post down on paper. I write until I run out of steam, which is hopefully near the end of the post, and then I leave the post alone for a day or two. When I come back to it, my job is to be a finisher and editor, not an author. This decreases stress and leads to a better finished product, since I’m almost never looking at both a blank sheet of paper and a deadline.
So too with rough draft packing: no stress about getting it just right, no running mental checklist in the background while folding shirts or counting socks. I know the main categories (work clothes, sleep clothes, exercise clothes, toiletries, etc.) so I just run through these categories and make a pile of folded stuff all in one place. Then, I return to that pile later, see it with fresh eyes, and start to make any obvious cuts (“am I actually going to swim on this trip?”), and find the things from my checklist that I’ve not gathered up.
Somehow this approach takes the stress out while also helping me pack right.
For more advanced tips (almost half of which, to my surprise, I seem to use), here’s a useful list from T+L.