How could I fix bowed legs without surgery?

You can't. Exercise may reduce symptoms such as pain, but only surgery can correct bow leggedness in adults.
Varus. Genu varum (bowed legs) cannot be fixed without surgery. Sometimes exercise can strengthen the muscles that support the knee, and braces can unload the medial side of the knee and temporarily straighten them. However, these treatments will not lead to a permanent change in the skeletal deformity.