Code to invoke a Macro when the user leaves the active sheet

I have a macro to sort a named range that works well but I need to have it run every time when a user leaves the active sheet. That way if they change anything in the named range, when they leave that sheet, it will re-sort that range. The code below is what I have to sort the range.

If anyone can help with my question or can simplify my code below, I would be so grateful.
RR

    Sheets("Project Role").Select
    Application.Goto Reference:="R3C2"
    Range(Selection, Selection.End(xlDown)).Select
    Range("B3:B42").Select
    ActiveWorkbook.Worksheets("Project Role").Sort.SortFields.Clear
    ActiveWorkbook.Worksheets("Project Role").Sort.SortFields.Add Key:=Range("B3" _
        ), SortOn:=xlSortOnValues, Order:=xlAscending, DataOption:= _
        xlSortTextAsNumbers
    With ActiveWorkbook.Worksheets("Project Role").Sort
        .SetRange Range("B4:B42")
        .Header = xlNo
        .MatchCase = False
        .Orientation = xlTopToBottom
        .SortMethod = xlPinYin
        .Apply
    End With
    Range("A1").Select