David, as an artist in training, I can remember by primary tutor teaching me some tricks. For instance, if you get bogged down--an emotional desert that gives you painter's block, turn the canvas to the wall for a while--maybe for months--and come back to it fresh after doing other work. Another trick is do some cross-disciplinary stuff. This can take the form of other media entirely--for me as a painter/printmaker it might be metal sculpture, paper making, or photography--or it might be a different approach within the same medium, go with a very disciplined super-realism if you tend towards non-representational work, or abstract expressionism if you really prefer drawing the figure or still life. The cross-pollination does us more good than we think.
I see you doing simply masterful stuff, and very much feel like a kid among giants with you, Michel, Louis, et al knocking around the site.
My next project (look for it soon) is a 1:35 WW1 Model T ambulance. It's a legacy build, given the year and all, in honor of my grandfather, Roger Burrell, who drove one in the Great War in an American ambulance unit that served with French troops. I've been putting it off, quite frankly, because it intimidates the daylights out of me, but it must be done, and I think it will be good for me.