Once you've found a pair of sunglasses that suits your face shape, it's difficult to toss them aside -- even when they aren't the right fit. Many sunglasses -- particularly the more inexpensive models -- are one size fits all, but inexpensive sunglasses can be stretched at home using heat to help mold them to your head. Just be sure to have prescription models adjusted professionally by an optician to avoid damaging the lenses.

Open the sunglasses and hold onto the ends of the arms. Gently extend and release them to gauge how far they can be bent without breaking.

Fill a bowl large enough to fit the glasses with hot water. Pull on a pair of rubber gloves to protect your hands.

Extend the arms of the sunglasses, and place them into the hot water so that they are completely submerged. Allow them to sit in the water for 10 seconds.

Remove the sunglasses and place them on a clean towel. Pat them dry with the towel to remove excess moisture, but leave the legs warm from the water.

Place the sunglasses on your head. Pull the legs away from your face and release them repeatedly to stretch them. Stop when they reach a comfortable size. Reheat the sunglasses if necessary for periods of 10 seconds.