Walking is the best to get blood pumping
Short answer - poor circulation. As to the cause of the poor circulation, see your physician if this is a true concern to you. Many people live with cold hands or feet all of their lives. On the other hand, there can be very real medical reason that you might want to consult with your doctor about.
Maybe you have poor circulation on that certain area..
See your doctor because poor circulation is really bad for your health you might even have dighabets ( I can't spell that but you know what I meen)