Old and Slow

I cannot draw fast enough. I am getting old and slow. Not long ago I could finish a 20"x16" pen and ink drawing with the entire board filled with ink in just a few days. Ideas for another project come to me when I am drawing. I have this image in my head but cannot begin to sketch it because this grasshopper illustration needs to get done. I suppose I can start the new drawing but I have this need to finish before I begin... I am afraid that by the time I finish, I would forget the image or my hands will draw something else.