Think back to when you were 25 years old. If you're not yet 25, then use a parent's 25th year, or uncle or aunt - or an older friend. Or, if you'd like, think ahead to when you will be 25.
Go to Google or Yahoo or whatever your favorite search engine is and put in that year, the city in which you were living (or would like to be living if you are future casting) and pick a month.
See what the top news stories were at that time. Pick one and write a story in which the news event has a role. Where might you have been? What colors do you see? What smells are in the air - the rain on hot pavement, electricity of lightning crackling through the spring air, dry hay, pork fat on the neighbor's barbecue grill? Who were you with? What were you doing?
Give yourself a couple minutes to find the event and have an image come to you - then write for 10 minutes.
