-memorize morse code (hard mode) or tap code (easy mode)
-learn how to spin a pen
-perfect your handwriting until you're happy with it
-learn (or get faster) at typing
-read a random wikipedia article and become an expert on it
(if you don't want pure random, here are some topics: hallucinations, poison dark frogs, lepidolite)
-learn how to solve a rubik's cube
-3d model something
-put time each day into learning a language
-try and get perfect/relative pitch
-play chess and really carefully think about each move
-expand your vocabulary so you can sound fancy when talking
-memorize the names of all bones in the human body
-memorize digits of pi
-learn color theory
edit: wow its been ~2 weeks and I have done none of this