i don't think anybody is completely even. nobody moves and holds their body in completely symmetrical ways all the time. we all tend to put more weight on one foot than the other, or cross one leg on the other when we sit, or use one leg on the gas pedal when we drive, or one hand for the mouse, or one hand for writing, or talking/texting on the phone, or tilting our head to one side or the other, etc. etc. every time you do this you create more tension on one part of your body than the other. and tension in one spot tends to pull another spot out of position, so pinpointing the "cause" of one particular pain can be a bit tricky sometimes. mostly this stuff is pretty subtle and we don't notice it until some sudden pain and we are like "where the hell did that come from?". i think good yoga can help this by focusing on alignment and feeling as much as we can, then stretching and holding postures based on what we feel. my teachers often suggest only stretching as far on your looser side as you can on your more tense side because if you keep lengthening your loose side it will perpetuate imbalances in your body.
i don't know if a lift would be the best way to deal with it. i guess if you have some skeletal imbalance, maybe, but if its just because of tension in your tendons/connective tissue/muscle/fascia it would likely cause more of an imbalance. i know i'd feel really weird with an insert in my shoes (especially after wearing vibrams for the past 4 years).