Turn the mattress 180 degrees. This will result in the former head of the mattress being at the foot of the bed.
Lift one side of the mattress up from the box spring. With a partner's help, lift one side of the mattress so that the mattress is resting vertically on the box spring.
Push the mattress gently so that it slowly falls over. With a partner's help, guide the mattress so that the side of the mattress that was previously on the right side of the bed is now on the left side of the bed.