When all your chores are complete, the worst thing you can do is slump in an armchair.
Even at rest you must think of your back.
DO sit upright in your chair with your back straight
DO use a back support or small cushion in the lower curve of your back
DO lie on the floor with your knees bent and resting on a cushion or low stool
DO use a firm mattress
DO fine a comfortable position in bed. Lying flat on your back is not always the best. Lying on your stomach with your head turned to one side may be the only comfortable position you can find, but it can be bad for your neck
DO get up and stretch occasionally, rather than sitting for too long
DO sit in chairs that are a good height for you