VBA To Hide Every Row From Last Filled Row Down

I have the following code:

Code:
Private Sub hidefixcells_Click()
'Hide the first 4 columns on all worksheets and adjust cells to fit automatically

Sheets("All Employees Annualized").Select
Cells.Select
Cells.EntireColumn.AutoFit
Columns("A:D").Select
Range("D1").Activate
Selection.EntireColumn.Hidden = True

[Code] ........

I want to add a vba to this code that will hide every row from the last filled row down. This will need to be done for sheets 1, 2 and 3. Currently, I am doing it manually, but I am hoping it could be done by code.