Countdown Timer

I have VBA code for a Countdown timer that works great for one cell per sheet, but I want it to work for multiple cells in the same column.

This code works for one cell. In this case it is referencing cell G6. But I would like to run the timer on any active cell in Column G.

I tried this (Set Count = ActiveCell.Range("G4:G100").Select), and some other variations of that same concept, but it does not work. I get error type "Mismatch". I'm completely stuck. Any help is much appreciated.

Sub Countup()

Dim CountDown As Date

CountDown = Now + TimeValue("00:00:01")

Application.OnTime CountDown, "Realcount"

End Sub

Sub Realcount()

Dim Count As Range
Set Count = [G6]
Count.Value = Count.Value - TimeSerial(0, 0, 1)
If Count <= 0 Then

MsgBox "Countdown complete."

Exit Sub

End If

Call Countup

End Sub