Are your shoulders up by your ears by the end of the day? Is your neck starting to get tight? Rolling out your back on a ball against the wall is a great way to release tension so you can get back to being productive and feeling great.
You're going to need a ball (I prefer a lacrosse ball) and a wall. The ball is going to be between your traps (big muscles on your upper back) and the wall. Lean back into the ball avoiding your spine. Roll around on these muscles and find any sore spots. Once you've relaxed one side, switch to the opposite side of your spine and do the same over there.
Why a lacrosse ball?
You can use a tennis ball for rolling out your muscles, and I do when I'm on the floor, but against the wall I prefer a lacrosse ball. The lacrosse ball is firmer than the tennis ball, and since you're not putting all your weight on the ball, a firmer surface helps you not have to work as hard. Lacrosse balls also have a tacky surface, they don't slide on a painted wall as easily as a tennis ball or baseball.