Early Stretch and Muscle Strained

I was asked to switch the power on for the boiler as some hot water was needed later in the day. The boiler is in a little corridor alleyway behind the washing machine and you have to reach over the washing machine to turn the switch. Being early in the morning my body wasn't warmed up and I twisted a muscle in my back with the stretch. Not as serious as my previous back injury but I know there are two or three days of pain to put up with.