Once you purchase shoes with the right fit, you then need to maintain them and replace them when they're worn out. The average life of most running shoes is 350-500 miles, but if you're a heavier or taller runner, or if your gait isn't smooth, you may need new shoes sooner. After a wet run, many runners throw their shoes next to a heater or put them in direct sunlight to dry. Over time, this will cause your shoes to shrink. Nor should you stash your running shoes in an unheated garage or on the outside porch in cold weather.
Cold temperatures make the midsoles harder and less cushiony.
It's best to store your running shoes in the house away from the heat after removing insoles or orthotics. If the midsole is compressed, brittle or feels unusually hard, it's probably worn out. If so, don't use the shoes for running. Gardening maybe, but not running. Examine Your Loafers Fit is just as critical in your nonrunning footwear as it is in your running shoes.