Sometimes I think it might be easier to be a completely new swimmer...one who has never swam before. I am a swimmer who breathes on my right side only and have done so for 35+ years. I am currently trying to "undo" those 35+ years worth of swimming to be able to swim with bilateral breathing, while also trying to be more efficient and faster in the water. I have been swimming since I was VERY young and have thus developed a relatively fluid swim stroke that only allows me to breathe on my right side and is not as energy efficient as I would like.
You might ask, why does breathing only on my right side pose a problem? Well...when swimming in an open water swim event (whether it is just an open water swim or a triathlon) it is much more beneficial to swim bilaterally. Bilateral swimming allows for a straighter swim and better sighting when trying to keep yourself on the swim course. It also provides you with the ability to breathe if the waters get choppy. If I only breathe on my right side and the water is choppy, I may have difficulty getting a deep enough breath without inhaling the water that may be continuously pelting me in the face. It also allows me to breathe if I have a swimmer next to me who is constantly making contact with me with their swim stroke. I can then choose to breathe on the other side and avoid getting hit in the face and potentially losing my goggles.
I have been trying to work on bilateral breathing off and on for a while now, but it wasn't until recently that I decided I am REALLY going to focus on this and try to make it stick. For whatever reason, breathing on my left side is NOT as easy and smooth as breathing on my right side. While breathing on my left side, I struggle with body positioning, rotation, windmilling of the arms while breathing and hand/arm placement in the water (trying to avoid the crossover). While knowing how much easier and better it feels to breathe only on the right side, I am determined to conquer bilateral breathing and become a much more efficient swimmer!!