Please read this:
http://www.allaboutvision.com/conditions/myopia.htm
Myopia has a significant genetic component, involving the inherited shape, especially the 'length," of your eyeball. The tendency towards myopia can be strengthened by factors in early childhood development. Once you are no longer a young child, there are no known remedies other than corrective lenses or surgery.
Glasses, contacts or refractive surgery.