while (<DATA>) {
  chomp;
  s/#.*$/ /;  # first replace any comments with space

  # skip this line if it consists only of whitespace (or nothing)
  next if /^\s*$/;

  # at this point we KNOW there is at least some non-blank on the line
  # which is also non-comment.
  # Just grab everything sans leading/trailing whitespace
  my ($non_blank) = /^\s*(.+)\s*$/;
  push @enabled_lines, $non_blank if $non_blank;  # 'if' may not be necessary
}