Like rest of body, you can keep your face firm and youthful as you age, by exercising the muscles regularly. Here are some exercises.

Entire Face:
-grin frantically pulling all muscles away from nose/center.
-pull entire face strongly into a tight knot around nose.
Alternate between the two and try to incorporate as many muscles as possible like neck, throat, scalp, tongue, ears etc when doing them.

Neck Crunch:
Lie on back. Slowly raise head until chin touching chest. Lower slowly.

Under Chin/Tongue:
-Apply pressure against curve from chin to neck. Close bite firmly. Press tip of tongue against lower front teeth to work muscle.
-While tilting your head back, press your tongue into the roof of your mouth, then bring chin down toward neck while still holding the tongue against roof of mouth.

Chin:
-Pull chin down w/fingers and curl the lower lip over the bottom teeth.
-Push lower lip up and down using chin muscle.

Cheeks :
-head back. three fingers on apples of cheeks and push down. raise cheeks by smiling.
-Push cheek out with thumb and bring the cheek back towards teeth against the pressure.
-Form an exaggerated "O" with your mouth by pushing your lips out as far as possible. Then smile is brightly as you can.
-pull bottom lip over top lip smile. Tilt chin slightly upwards until feel pulling on neck.

Eyes :
-partially winking one eye at a time, and holding the wink for a second, and then repeating the movement.
-Place three centre fingers underneath the eye, pull down, and try to close your eyes.
-Place the ring and middle fingers at outer corners of eyes and pull toward the hairline, while squeeze eyes shut.
-place index fingers under eyebrows. Push up while closing eye.

Mouth :
-Pull lower lip down with fingers and try to mope.
-Open mouth wide like yawn. Pull in the sides to form an oval. Now curve lips over teeth. Then close lips until 1.5cm apart.
-Hook sides of mouth w/fingers and pull out while making an 'o' mouth.

Forehead :
-Pull the eyebrows w/fingers, and try to move them in opposite direction. Do this for inward, outward, up and down.

Links:
http://www.shapeyourface.com/
http://haha.nu/interesting/facercises/
http://haha.nu/interesting/facercises-part-2/

Authors:
Senta Maria Runge
Marjorie Craig
Carole Maggio
Meir Schneider
Cynthia Rowland
Ade Adeyemi Coles