If your back is feeling tight at the end of the day releasing your lats could help. Our lats are a big muscle that attaches to the front of the upper arm bone and fans out to the upper spine. I use a Franklin Easy Grip ball in the video, but if you don't have one you can use a foam roller to start (until you get one :-).
Check out this quick video on how you can do this yourself during the day, before a swim, run or walk or at the end of a day on the computer! Click to check it out, or watch it below.