warming up to play... Movement is the key because the body needs to warm up before I even think about my instrument I think – unless of course it's your voice.  So I walk around moving my arms, then I stand still and swing my arms - a Feldenkrais movement - this gets me breathing well - opens up the ribcage.   I also sit in my chair on my sitting bones, and do the pelvic clock forward backward and side to side, with sitting in neutral as the center of the clock.  Then I can play some music... But I still take breaks to move all of me...