Stop a running macro

This was my first attemp at writing code. These lines are only for the first value. I have 20 additional InputBox statements. The reason for a method to stop the macro is many individuals running the macro and getting interrupted while inputing data.

Sub Fill01()
Worksheets("SINGLE PHASE CONSTRUCTION").Activate
    Dim UserEntry As String
    UserEntry = InputBox("What is the W/O #?", "INPUT W/O")
    If UserEntry <> "" Then Range("B2").Value = UserEntry
END SUB