It’s really not that difficult to switch. When driving, just make sure the driver is toward the middle of the road and the passengers are on the side of the road.
I make the switch frequently. I am a US citizen and I work in Indonesia. The only problems occur is when there is no other traffic on the road.
You should see my kids though when I drive on the left in the US. They really hollar at me, “MOM GET OVER YOU’RE IN THE MIDDLE!!!!” Me: “NO ONE ELSE IS AROUND. WHAT’S THE BIG DEAL?” I try to do that at least once when I’m in the states.
I work in a surface mine with left-hand traffic, and switch over every day at the gate. The mine roads are unpaved, so I seldom find myself driving on the wrong side on pavement, but I often drive to the left on dirt roads now. Around here, though, most of the other people driving on the back roads also work at the mine, so they’re likely to be on the wrong side too, and it all works out.