For daily warm-up see Naming the World edited by Bret Anthony Johnston, Random House, Random Inc. 1745 Broadway, New York, NY 10019.
Four examples : describe a doomed wedding, places you’ve visited where you don’t ever want to go there again, or describe a car wreck or an unwelcome surprise.
The book is filled with good advice by authors who share their favorite writing lessons.
Also see What If by Anne Bernays and Pamela Painter.
The Three O’clock Writer (check title)