Learn through joy

I have a deck of flash cards created by Mikelle Terson so I can learn the yoga asanas by their Sanskrit names. For example,

Adho Mukha Svanasana = Downward Facing Dog
Urdhva Mukha Svanasana = Upward Facing Dog
(Though in classes they are shortened to updog and downdog.) 

The last card in Mikelle's flash card deck says...

"Learn through joy."

And it always makes me smile when I flip past that one.  Learning things that don't interest you sucks.  You have no retention for it. But learning things that give you joy provides endless capacity to retain, to explore, to go further...  It would seem that joy may be the biggest clue in what it is that we should follow after.