If learning can be so much fun even as a grown up, heck, who wouldn't want to sign up?
No, learning ought to be fun. For what is fun but the lighting up of one's spirit? Learning -- in my humble opinion -- ought to be a process that in fact lights up one's spirit. Isn't that what the term 'enlightenment' is all about, to the point that it is no longer just a metaphor, it is taken to be literally what the term suggests.