The anger energy IS the energy that is wanting your face to snarl, and to beat the shit out of someone and shout. The fear and sadness are most likely part of the internal mechanisms that have helped keep this anger energy at bay. The idea is to try and stay connected to the more aggressive feelings and how they may want to play out, remembering to keep your motions slow, and to stay connected to your body. You can acknowledge the fear and sadness as real, but understand that they are part of what has kept this anger suppressed, and aren’t that useful for this particular work, though of course it’s a good idea to make space for them afterwards, should they still be around. Often times rage will alternate with grief like layers of onion.