Returning to playing the concert flute after many years away, and starting to practise with with rebuilding the embouchure (the strength in the lips and control of air - a fundament of the instrument). The way this is normally done is by taking only the head joint of the flute, and creating a sustained single note, through adjusting the position of the lip-plate on the lips and also the position of the mouth and airstream over the plate. As you can tell, I'm very, very rusty! This is a type of muscular exercise, and as such takes a long time to work up to full strength.