the backs of my ankles kill me each morning

each morning when I get out of bed or if I am sitting and resting for a spell, when I first start walking the backs of my ankles are stiff and sore and painful.
I am not much of any active person and do not participate in any sort of sport, but in the past I did a lot of power walking and was not one to stretch a lot.
I think I am now paying the price of that.
Is there anything that I can do? they quit hurting once they get “broken in” and won’t start huring again until they get rested and then it starts all over again. thanks so much!