Select a cell in worksheet and choose:
Ctrl+Shift+right arrow – highlight from current selection all the way to the right
Ctrl+Shift+left arrow – highlight from current selection all the way to the left
Ctrl+Shift+up arrow – highlight from current selection all the way to the top
Ctrl+Shift+down arrow – highlight from current selection all the way to the bottom
With Ctrl+Shift pressed, press right arrow first and then down arrow to select from current selection all the way to bottom-right corner.