Place the following in your "ThisWorkbook" module inside the vba editor.
' Upper_Case Macro
' Change Value of Selection to upper case
' Keyboard Shortcut: Ctrl+t
Dim myCell As Range
Set myCell = Application.ActiveCell
.Value = UCase(.Text)
Then assign a shortcut to run the routine. (I use Ctrl+Shift+T) Then as you work in excel, you can select a cell that you want to format as upper case text and press your shortcut to reformat it.
...now back to work!