A toned physique will help you appear years younger; from afar. But unless you're exercising the muscles in your face, factors like gravity and stress will give away your age by pulling down the corners of your mouth and exaggerating your jowls. By practicing a couple of yoga techniques for a few minutes every morning and evening, you can tighten and shorten your facial muscles.
Lion is an old-school yoga pose. There are two versions described in yoga master B.K.S. Iyengar's book "Light on Yoga." But you don't have to assume the full poses to experience the benefits. The facial portion of Lion can be performed on its own. Sit in a comfortable cross-legged pose on the floor. Open your jaws as wide as you can and stick your tongue out. Look up toward your eyebrows and breathe through your mouth in this position for 30 seconds. Repeat twice more.
Annelise Hagen developed the very modern technique of facial yoga to combat wrinkles and tighten the muscles in your face. Since the "Satchmo" technique exercises the muscles of your cheeks, you can help lift your jowls over time. Inhale with your mouth closed and fill your cheeks with air. Pass the air back and forth from cheek to cheek. When you're out of breath, take another large inhale and repeat.