Install an air support system between your mattress and box spring. These are available at most home and department stores.
Inflate each chamber of the air support system with an air pump to repair the saggy part of your mattress.
Fill the chambers with enough air to suit your desired level of support.
Purchase a patch repair kit to fix a faulty air mattress. Bring 1/2 qt. of water to a boil and place the pouch of bonding material in the boiling water. Heat for three minutes.
Open the valve on your air mattress and lay the mattress out flat. Ensure the repair area is clean and dry. Cut a patch that covers at least 1/2 inch beyond the hole all the way around.
Remove the bonding material from the boiling water and apply a dime-sized drop to the hole. Cover the area around the hole with the bonding material in the shape of the patch.
Apply the patch and center it over the hole. Place a plastic bag over the patch and set the pan of hot water over it for 1 minute. Take the pan off and roll over the patch with a water bottle or rolling pin.