I'm trying to identify what is either a mythological story (likely from the Greco-Roman tradition, but not necessarily; could be an Aesop thing, or similar), or a short story. The plot is as follows, to the best of my memory:
A young man/woman comes across an old woman (a witch, maybe) with a box. The box has a string in it, coming out of a single small hole in the box. The string may be red. She offers the young man/woman a chance to pull the string from the box, which will make him/her older. The only stipulation is that the string may not be returned to the box, and that consequently any increase in age cannot be reversed. The man/woman greedily pulls the string from the box, only to pull too much, and reaches the end of their life.
Any ideas as to where this came from?