I was told by Roger Woodward not to let the music play you, but you play the music.
I don't know who Roger Woodward is, but I completely disagree with his statement. In my opinion, his statement suits material, touchable things; for instance, it would be right of him to say: "Don't let the computers/machines rule over you, but you over the computers". Or: "Don't let alcohol rule over you, but you over the alcohol."
But isn't music something higher than material things? Shouldn't we apply another standard for art comparing to the "real world" - a world filled with things that we can control? Because the truth is that control restricts the freedom in doing things however you want to do them, and in my opinion, the desire to control everything is going to make music as boring and bureaucratic as the KGB police under Stalin in the Soviet union. We need to let the music speak, and the only way to do it is by letting it fly - free from boundaries, free from control. Anything else is going to be predictable and dull.
It's not YOU who should play the music, the music should play you. It should make you feel something - happiness, sadness, sentimentality, whatever. And these emotions will be found in the pieces that you're going to play - so just let the MUSIC tell you what to do... in other words, the "instructions" for how to play a piece won't come from a good teacher, the performance commentary or in the sheet music, but only from the sound of the music itself. (I'm not saying that good teachers are nothing worth) Therefore, the only way to get an idea of how to play a piece is, in my humble opinion, to let the music itself reveal this for you. Anyone can learn all of the ornaments, get all editions and read about the composers... but if you want to make a good interpretation of a piece, just let the sounds you hear guide you.
To relate what I've just said with the topic itself, I can only say that just as we shouldn't try to control music (and instead letting the MUSIC play you, rather than you play the music), we shouldn't try to control what we FEEL for the music. Art and emotions are infinately free and are not restricted to any boundaries. We don't "decide" to feel anger or love towards someone, it's simply emotions we cannot control.
In the same way, NO MUSICIAN should try to control the river of emotions that pours out at the moment that beautiful music is being created. It's just something that happens. Everything is a part of the creation, and if you try to control the musicians feelings towards the music, you'll change the music too. In the end the music won't feel real or emotive, and what once was looked upon as art - which is something higher and "better" than the "real world" - will become another product of entertainment for the masses who are more concerned about if the performing artist is wearing the right clothes and has shaved himself during the recent days than if the artist is actually out there on the concert stage to communicate through the instrument. With or without body movements.