Shitty background worker and incompetent async practices

MainPage.xaml.cs

public class MainPage : MyAppPageBase
{
    public Budget()
    {
        InitializeComponent();
    }

    public async override Task MyAppPageDoWork()
    {
        if (_isNewLoad)
        {
            _viewModel = await DeserializePreviousRunsViewModel();
            DataContext = _viewModel;
        }
    }

    public async override Task MyAppPageDoWorkCompleted()
    {
        // Initialize the view model
        if (_isNewLoad)
        {
            _viewModel = await new MainPageViewModel();
            DataContext = _viewModel;


            _isNewLoad = false;
        }

        // other page loaded specific stuff
    }
}

MyAppPageBase.cs

public class MyAppPageBase : PhoneApplicationPage, IMyAppPage

{
  void MyAppPageBase_Loaded(object sender, System.Windows.RoutedEventArgs e)
  {
      var bg = new BackgroundWorker();
      bg.DoWork += delegate
      {
          Dispatcher.BeginInvoke(async delegate
          {
              await MyAppPageDoWork();
          });
      };
      bg.RunWorkerCompleted += delegate
      {
          Dispatcher.BeginInvoke(async delegate
          {
              await MyAppPageDoWorkCompleted();
  
              if (ApplicationBar != null)
                  ApplicationBar.IsVisible = true;
          });
      };
      bg.RunWorkerAsync();
  }
  
  public abstract Task MyAppPageDoWork();
  public abstract Task MyAppPageDoWorkCompleted();
}