I have problems like you are describing on rainy Mondays only because every Monday we are out of this place by 9am! They are always happy outside. Our central library has a storytime and a playroom and that's where you find us every Monday possible. By the time we walk there, play all morning, walk home, they are ready for lunch and bed and a nice long nap.

So there's my advice - take them out and RUN THEM!