You do have spare time. It's those moments when you're waiting for your coffee or your ride or the elevator at work. My first instinct is always to pull out my phone and start internet wondering or over checking my email.
My cousin Jules and I have decided to spend that time learning! What if you kept a small set of flashcards in your pocket and pulled them out instead of your phone? You could learn how to say hello in 10 languages, state capitals, measurements for work, cooking conversions, etc. I think I'll try learning mid-century designers.
Try it out for a few days and then have someone test you. I'll bet you'll learn and retain more information that you can imagine.
(photo from Etsy shop Please Be Still)