Those need to be either replaced or strengthened. Replacement is simple, but expensive. Solid core wooden or steel doors are recommended. If the cost of replacement is too expensive for you, look into the possibility of strengthening the door with plywood, sheet metal or plastic. Even better is a sheet of galvanized metal.
Salvage yards are good sources for such materials.
Glass in doors can be covered by one of the modern plastic materials available. We recommend an acrylic, such as Plexiglas or Lucite, or a polycarbonate, such as Lexan. These are also excellent materials for replacing conventional window glass. These materials have different abilities to resist scratching and breaking. Consult with your building materials salesman or hardware store clerk for detailed information on these features.