How to annoy yourself by been forgetful

Nothing is more annoying when I come back from a trip only to find the photos I took are far from ideal. And this was what happened to me for the batch of pictures I took in Memphis, Saqqara and Giza. I forgot to change the ISO from 400 that I had used the night before back to 100 and ended up with unusually grainy pictures taken in 37 degrees sunlight...arrggggggg!