Imagine that one of your fictional characters has pulled an old family photo album from a shelf. He retires to a couch to look through it. What does he find? Describe at least one of the photographs—something that surprises him or catches his attention—in detail.
This could be a photo album that belonged to a previous generation, or one from his own childhood. If you don’t tend to write about modern or futuristic worlds, you can substitute some sort of sketch book for a photo album (perhaps a family member possessed some artistic talent and liked to draw other family members or unusual occasions).
As an alternative exercise, look through photo sites on the internet and pick a photograph to represent the one he finds; write about it and how it fits into his life and family.