Ever since I worked as an assistent nurse at an elderly home in 2007 I have had lumbago - which is sever ache in the lower back. Fortunately this is not a chronical condition but I have lumbago around twice a year. My sister-in-law is a physiotherapist and she sent me a compilation of some exercises I can do at home over the internet from her workplace. If you also suffer from pain in the lower back or you just want to prevent ever having it this is what you can do:
You should do 3 rounds with 12 repetitions of each exercise. The whole workout should last about 20 minutes. These exercises have helped me enourmously (on Wednesday I couldn't walk straight and today Saturday I went hiking for over three hours). Also walking is highly recommended, even though it hurts. Hope this helps :-)