$l = "sentence to format.  This is a sample sentence to format.  This is a sample sentence to format.  This is a sample sentence to format.";

 use Text::Wrap;

  $Text::Wrap::columns = 52;
  print wrap("    ", ' ', $l), "\n\n";
__END__
    sentence to format. This is a sample sentence
 to format. This is a sample sentence to format.
 This is a sample sentence to format.