Have them replaced whenever they appear cracked, brittle, frayed, become loose or show signs of excessive wear.

FORBES: Cars That Can Last For 250,000 Miles (Or More)

Look for other signs of excessive wear on the arm-rest, the floor mats, the pedals for the brakes and gas, and the area around the ignition.

FORBES: Feds Charge Pair with Sales of 247 Mileage Tampered Cars

Conventional wisdom holds that the pounding from years of running leads to excessive wear and tear on the body as we age, resulting in joint injuries, knee replacements or arthritis.

CNN: No need to hang up your running shoes as you age

"Chronic extreme exercise appears to cause excessive 'wear-and-tear' on the heart, " the editorial says.

WSJ: Endurance Sports: Studies on Older Endurance Athletes Suggest the Fittest Reap Few Health Benefits