None. If you're talking about a baby, then bowed legs often straighten themselves out. If you're talking toddler at or around age two, then you need an evaluation from a pediatric orthopedist. If you're asking about an adult, then the answer is still none. The shape of your legs is the shape of your legs. But exercise is still a good idea.
Bow legs. Childhood bowing usually corrects unless a more severe growth plate or blount's disease. Adult bowing with boney deformity usually doesn't correct--bracing can help symptoms, may eventually be looking at surgery if painful & exhausted conservative means.