Broody hen

Lizzie has taken to nesting under the nest boxes and sitting for hours on end. We're trying to break the cycle of her brooding as none of the eggs are fertilised so there is no hope of hatching! Apparently they will only sit for a maximum of three weeks as that is how long it would take for an egg to hatch. How she will know when the three weeks has passed, as there will be no chick, I have no idea. We are lifting her daily to make sure she eats and drinks but she just returns despite there being no eggs to sit on! I have to say I feel a bit sorry for her.