A door-mounted exercise apparatus which includes: a first strap, measuring essentially 1.5 inches wide, essentially 73 inches long, and essentially 0.0625 inches thick, operable to removeably circumnavigate a door along its width, said first strap further including: a) a buckle operable to adjustably tighten the first strap circumferentially around the door's width, such that a user's feet can be inserted between the first strap and the door to securely adhere the feet up against a front or back surface of the door, and; b) a fastening device, said fastening device affixed to the first strap and operable to removeably fasten an elastic band to the first strap, such that the elastic band can be stretched by the user to exercise arm and leg muscles, wherein said fastening device includes any of the following: Velcro®; snap; button; buttonhole; carabiner; clip, and; ring; Whereby the door-mounted exercise apparatus enables the user to perform sit-ups and other muscle strengthening exercises.