We always feel the most important thing is how you're holding your mind and your heart. But I don't think that's what this person meant. Physical posture: your back. If you can, try to keep a straight back, whether you're sitting cross-legged, whether you're on a bench or whether you're on a chair. But if your back's beat up and you've got too much pain, if you get to my age and you've got lots more pain than you used to have, then sometimes you've just got to relax your back. But in that sense, then what I said first about what you are doing with your mind. How are you holding your mind, how are you holding your heart? Is that getting sloppy, are you falling asleep in your mind and your heart? So, that's most important. But as to the physical posture, try to keep a straight back is generally what we say.