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The ideal way of doing this would be that you develop such a strong link between what you hear in your head and what your body does to make it happen without any conscious thinking at all.
The way to develop this would be playing a lot by ear. This is easier said than done. It could turn out that one does not know the music well enough to start with. This process is particularly odd for a good reader. On top of that, there are apps that transpose a lead sheet with a simple push of a button.