Ok, the inversion/eversion problem. Inversion is when your foot turns in, eversion is when your foot turns out. Ever hear of someone “rolling their ankle?”. That means that they sprained the ankle(stretched the ligaments too much) by over-inverting it during walking. Actually, the complete motion is called supination of the foot. Supination of the foot is the combination of inversion and plantarflexion (plantarflexion = pointing the toes downward). So if you roll your ankle, generally you over-supinate your foot. Pronation of the foot is the opposite of this. It’s a combination of eversion and dorsiflexion (pointing the toes upward and lifting the foot). To help rolling in of the ankle, you want to get your pronation muscles as strong as possible. The muscles on the outer side of the lower leg that control eversion are called the peroneal muscles. And you want to strengthen the dorsiflexion muscles too, I wrote about this. You want to strengthen everything in the ankle, but really focus on the pronator muscles. Do this, and this, and this, and these. By the way, when your foot is naturally overpronated, that’s what they call flat feet.