Replace your walking shoes when they start to show real signs of wear and tear. This might look like worn out tread, torn mesh, or delaminating layers. Be mindful of replacing them too soon—a tiny hole in the upper might not look nice but is probably nothing to worry about, and most walking shoes should last for 300 to 500 miles and even beyond. Repair or resole them when you can (especially if they're boots), and check the brand's warranty program if they seem to fall apart too soon.