Have gone to Life Drawing on and off the last twenty odd years you get to know when a particular session is just not going to go well. Those times when you just cannot put a line down right, and the situation grows worse. Going round and looking at everyone else’s works at the tea break helps little. Time to wash brushes and palette, swear under one’s breath and move on.
It maybe all in the mind, and ‘all in the mind’ might be the definition of drawing anyway.