Set the path separately e.g. as follows. This assumes that strPath exists and that the bookmarks and content controls exist in the documents. If not you will have to introduce some error correction.
Sub Test()
Dim oDoc As Document
Dim strFilename As String
Const strPath As String = "F:\Joe\Test Folder\Test Destination\"
strFilename = Dir$(strPath & "*.docx")
While Len(strFilename) <> 0
Set oDoc = Documents.Open(strPath & strFilename)
With oDoc
.Bookmarks("Discip").Range.Text = strDiscip
.Bookmarks("ProjectNumber").Range.Text = lngProjNum
.Bookmarks("Rev").Range.Text = "A1"
.ContentControls(1).Range.Text = Me.cboClient.Value
.ContentControls(2).Range.Text = cboAsset.Value
.ContentControls(3).Range.Text = txtWpkDocNo.Value
.ContentControls(4).Range.Text = Me.cboDiscip.Value
.ContentControls(5).Range.Text = txtWpkTitle.Value
End With
Debug.Print oDoc.FullName
oDoc.Close wdSaveChanges
Set oDoc = Nothing
strFilename = Dir$()
Wend
End Sub