Not that uncommon.
I do a lot better if I'm shown what to do, or have a written list to go back to when I get forgetful.
Tell people you have a bad memory, carry a small pad of paper in your pocket. Ask them to write down instructions, or show you "the first time" how to do it. They'll usually get all huffy but they'll show you how to do it.
I think one of the main reason instructions tend to be forgotten is because a lot of the people giving the list of instructions are not giving enough details. This means our heads are trying to solve how to do the first instruction (trying to fill in the details, answer all the questions) while they are already giving the second instruction. Along the way, one of them gets lost because our heads are too busy already. Then "poof" there is too much we missed and we get flustered.
"Go weed the garden, then go to the post office and mail this, then get pizza with green olives and extra cheese."
They're done the sentance, and we're still thinking "Do I know the difference between a weed and a flower, and if I make a mistake, what's going to happen?"
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By simply doing what they are designed to do something large and magnificient happens. In this sense they show us how to live; The only barometer you have is your heart. When you spot your flower, you can't let anything get in your way. - John Laroche