Cooking too much for dinner is a great way to have lunch for work the next day. Before putting leftover food in the fridge, make sure its had time to cool down. While you never want to leave perishable food unrefridgerated for more than an hour, letting your dinner chill out for a sec will prevent the hot food from raising the internal temperature of your fridge. A warmer temperature means more energy used to cool back down, and can also affect the integrity of other foods in the fridge. Bringing your lunch to school or work will save you money, and keeping your refrigerator functioning properly will too.