For any given substance, the heat capacity of a body is directly proportional to the amount of substance it contains (measured in terms of mass or moles or volume). Doubling the amount of substance in a body doubles its heat capacity, etc.
Conventional soft contacts can last up to a year; conventional rigid gas permeable (RGP) contact lenses can last even longer. Frequent or planned replacement contact lenses last one to several months. Disposable contacts last from one day (daily wear) to up to two weeks (extended wear).
What you're doing: You've been using the same contact lens case for as long as you can remember. Why you should stop: First things first: Go to your bathroom and throw that old case away. Contact lens cases should only be used for three months tops before you replace with a new one, Thau says.