Keep your head up, be scanning several cars ahead, and look for driver's small movements. That generally telegraphs their next move. If you find yourself caught by surprise very often, you're just not good at it from an intuitive level, and should back off from it.
If you're going to stop lane-sharing at 70 mph please do a favour for those that go a little faster, and get out of the lane-sharing position between the #1 and #2 lanes.
A little bored? Try splitting semi-tractors - that's kinda fun if you are finding life a little dull.