Aka "Walking." 😎
You may have never thought about this, but continuing to walk in shoes that are worn out or poorly suited to your gate or walking style may be holding back your progress. The reason this matters is biomechanical. Every step we take involves a complex chain of forces moving up through the foot and ankle and knee and hip and also lower back. And each joint in that chain depends on the one below it absorbing and distributing the force correctly.
When the cushioning in your shoe has worn down, which can happen very gradually and invisibly, that force goes directly into your joints instead. Studies have shown that worn out shoes significantly increase the stress placed on the knee joint with every single step in ways that are associated with worn down cartilage over time. All of this happens very gradually. There's no sudden pain or obvious sign. It just accumulates very gradually, step by step and walk by walk.
Most walking shoes maintain their cushioning for around 300-500 miles, give or take. After that, the shoe is no longer doing its job.
As you can see, in the past year I've averaged around 250 miles a month in my shoes. I have found that after 300-400 miles my shoes actually start working against me and need to replaced. This means I need to buy a new pair of shoes (I always get the Altra brand) about every 2 months. This isn't about buying really expensive shoes. But please make sure you are not "shooting yourself in the foot" by continuing to walk or run in worn out shoes.
Have a blessed (peripatetic) day!