Learn different kinds of meditation really well (loving-kindness, concentration, insight). This can also be practiced at any time.
Learn some poems with fluidity (this can of course be done with spaced repetition). If you learn for long enough, maybe you can learn parts of an epic. If you want to be really impressive, learn it in the original language (however, try to get the pronounciation right!)
Make predictions until you know you’re well calibrated
Personal additions:
Learn different kinds of meditation really well (loving-kindness, concentration, insight). This can also be practiced at any time.
Learn some poems with fluidity (this can of course be done with spaced repetition). If you learn for long enough, maybe you can learn parts of an epic. If you want to be really impressive, learn it in the original language (however, try to get the pronounciation right!)
Make predictions until you know you’re well calibrated
Try to be mindful of your posture – how straight is your back, where are your shoulders? Maybe set up a random timer that reminds you to do this
Learn the basics of dressing well, then refactor your wardrobe (starting point for men, practical information for women seems to need no resource)
Learn the basics of investing, and actually put some money into it