Como rodar uma rotina em segundo plano?

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ExtCtrls;

type
  threadDisparaRotina = class(TThread)
   protected
      procedure Execute; override;
   end;

  TForm1 = class(TForm)
    Timer1: TTimer;
    procedure Timer1Timer(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Timer1Timer(Sender: TObject);
begin
   Timer1.Enabled := False;
   threadDisparaRotina.Create(False);
end;

procedure threadDisparaRotina.Execute;
begin
   // Executo aqui o que preciso
end;