When you say 'can't dance through a whole song' do you mean 'can't do frenetic club dancing' or do you mean 'couldn't do a box waltz or cha-cha or other relatively low key dance step' for a whole song? Because sometimes I can manage the latter (although the usual such dance around here is known as the Canadian Two-step), and that is enough to move enough that the 'having been lying down too long' pains settle just a little.