High-school reunions can be a shock. Everyone attending is about the same age, so why do some classmates look amazingly young while others look at least a decade older than the rest?

Genes play a significant role, of course. Grandma Esther's smooth, wrinkle-free skin may have been passed down to future generations, along with Uncle Jake's slim physique. But other factors can also have a profound influence on how gracefully you age.

8 Things That Add Years to Your Looks

None one can turn back time, but you can avoid these common offenders that can make you look old before your time.

  • Unhealthy weight
  • In addition to increasing your risk for diabetes and heart disease, extra pounds can add years to your appearance. On the flip side, being too thin is not becoming (or healthy) either. Stick to a regular exercise routine, which is good for your heart as well as your skin; increased circulation can promote a fresher-looking face.

  • Lack of sleep
  • Not getting enough z's can contribute to puffy facial skin, as well as dark circles and bloodshot eyes. Being perpetually overtired can also lead to an increased risk of heart problems.

  • Smoking
  • We all know that smoking is damaging to our lungs and other organs. But it's also extremely hard on the skin. Smoking slows blood flow in the face, and the sucking motion made while inhaling produces vertical lines around the lips. Kicking the habit now will improve your overall health, both inside and out.

  • Too much sun
  • Few things age a person's appearance as much as rough, leathery skin due to tanning. Instead of looking healthy, it's often lined and spotted. Plus, it can increase your risk for developing skin cancer. It's not too late to reverse the trend, though. Apply a broad-spectrum sunscreen with an SPF of 15 or higher every day, and stay out of direct sunlight. Wear sunglasses to protect your eyes from harsh rays and to prevent wrinkles that come from squinting.

  • Excessive makeup
  • As one ages, less makeup is almost always better than more. Heavy foundation can settle into wrinkles, and shiny or brightly colored eye shadow can emphasize lines around the eyes. Many department-store cosmetic counters offer free makeup consultations to help you try out a new look. Focus on highlighting a single feature, such as large eyes or full lips.

  • Outdated hairstyle
  • Stuck in a time warp when it comes to your 'do? Some women keep the same hairstyle year after year, which can be very dating. Consult with a hairstylist about updating yours to a more modern look. In addition, hair coloring can do wonders when it comes to looking younger.

  • Inappropriate clothing
  • Age-appropriate clothing doesn't have to mean housedresses and "sensible" shoes. There are a variety of comfortable, attractive fashions for people of all ages. Accentuate your best features, such as long legs or a swanlike neck. Color can also make a big difference in clothes. Don't be afraid to add rich tones to your wardrobe.

  • Bad posture
  • As your mother always said, stand up straight. Good posture is not only beneficial to your body; it also makes you look taller and slimmer. What's more, good posture can convey self-confidence, which may just be the best accessory you can have.