By the way, in terms of knee pain specifically you may find that changing your footwear and/or running style can alleviate it. Landing on your heel puts a lot more force through the knee joint compared to landing on the middle of the foot. Traditional running shoes are designed to land heel first, which is why they have so much cushioning, but you can buy lower profile shoes that allow you to run differently. This will redirect load to your calves, though, so you'll likely need to strengthen those before being able to run whatever distance you're currently comfortable with.