using Thread in windows phone 8.1

private void Start_Example()
 {
     for (i = 0; i < 1000; i++)
     {
         Thread.Sleep(100);
         this.Dispatcher.BeginInvoke(() =>
         {
             lblResult.Text = i.ToString();
         });
     }
 }

 private void btnStart_Click(object sender, RoutedEventArgs e)
 {
     ThreadStart st = new ThreadStart(Start_Example);
     Thread s = new Thread(st);
     s.Start();
 }