If you work for up to eight hours on your computer, make sure you stretch your back to prevent any health problems that may appear as a result of your sedentary lifestyle.
Sitting mostly affects lower back, causing a huge pressure, which can later result in severe health problems. Watch the following video and perform these exercises on a daily basis.
You will notice some improvement right away, and do not worry if you cannot stretch as professionals do. It may take some practice before being able to master in doing these exercises.