Okay a great way to stay sharp, take an object from your studio and do ten sketches :10 min.... (insert some lame joke about unlocking the creative psyche) I like staying sharp, but Lee took all the sharp objects out of the studio... So a Google-Eye works..... If you want to see more "Staying Sharp," see Staying Sharp #5.
Right brain thinking....So it's a little exercise I started when I was in art school...Doesn't have to be brilliant, just a great way of staying fresh and keeping the ideas flowing. Honestly, this little set of drawings only took :10 but then another 20 minutes or so to scan them and figure out how to post them....but you get the idea.