Copy a piece of your writing to a new file. (Nonfiction works best, but you can try this exercise with any genre.)
After every sentence ask yourself, “How?” or “Why?” and write the answer after the sentence that inspired it. Here’s an example:
Original: There were ducks on the pond.
(I ask myself: Why were there ducks on the pond?)
Revision: There were ducks on the pond. Ducks are big fans of ponds, and will sit on them whenever they can find an empty one.