I walk on the wrong side, too. Whenever I’m on the stairs, or even if I end up in a sidewalk/hallway sort of situation most times, I don’t even realize that I’m in the left side until I reach oncoming traffic. At those times, I resort to my Japan automatic behavior of scooting simply to the middle of the stairwell, as opposed to switching sides entirely. While escalators and roads were set sides, stairwells and walkways often had signed alternate setups for walking (due to high traffic in train stations and such), so I regularly was too confused when either there weren’t signs or people united them. It quickly became a habit of mine, especially at school, just to put myself in the middle of the stairwell, and to let people go around me as they pleased.
And now I find myself always starting on the left side, and pushing quickly to the center as people approach, just like in Japan. I find it amazing, the habits we build in life.