Much of this slots into time outside work rather than the workday itself.
- walk a different route to a destination
- pick an algorithm and walk with no destination (eg: straight until you hit a light not in your favor, then turn. Works in urban envs)
- go somewhere you don't normally go. Eg: library, different coffee shop, that little art store you always see
- go to the library. Walk along the shelf with eyes closed and pick a book at random.
- pick a genre of music you never listen to. Listen to it.
- cook or prepare a meal unlike your normal fare
- go to a thrift store. Buy a cheap article of clothing you wouldn't normally wear. Wear it. See how it feels
- find free or cheap art (music, theater, whatever) in your area. Go.
- journal. Spend a few minutes writing down your day's details
- hit wikipedia's random article button. Read it.