Not all knee pains are the same! Here are some structures to consider if your pain is more to the inside or back of the knee.
Above is the popliteus. It is involved with the slight rotation of the lower leg for 'locking' and 'unlocking' the knee and is located in the back of the knee.
Below is the sartorius. It has to do with rotating the hip (into pigeon pose), but also influences lower leg rotation.
There isn't a recipe for dealing with knee pain because, even though the symptoms may sound exactly the same, the cause for why you have it varies greatly. What IS consistent about knee pain is the influence of the hip joint from above and the ankle joint from below. Best physical therapy practice will treat more than the isolated area and assure you don't have to "deal with it". There IS a solution because the idea of "having pain as you age" is not the truth; it's just something we got used to saying.