How do I make my macro run when 'save' is selected?

I am setting up a document to remove rows if a specific cell contains a value. I want this code to run when the 'save' button is selected. What do I need to add to my vba script to make this happen?

I have searched several sites and tried several suggested solutions but am not finding one that is working.

HideRows_BeforeSave()

Dim beginRow As Long
Dim endRow As Long
Dim chkCol As Long
Dim rowCnt As Long
Dim rngResult As Range
Dim ws As Worksheet

beginRow = 3
endRow = 38
chkCol = 14

Set ws = ThisWorkbook.Worksheets("Travel Expense Codes")

For rowCnt = beginRow To endRow
    If Cells(rowCnt, chkCol).Value = "X" Then
        Cells(rowCnt, chkCol).EntireRow.Hidden = True

    Else
        Cells(rowCnt, chkCol).EntireRow.Hidden = False

    End If
Next rowCnt

When this code is inserted into the 'ThisWorkbook' object I am getting no response when I run the macro. When inserted into a 'Module', I can make the macro run but am not able to make it run with the 'save' selection.