I listen to music to focus (while I love the silence, lately I've found that when it comes to studying, I need some sort of background noise to keep going).
Every two hours or so, I would reward myself by eating some candy. Mostly chocolate.
Sometimes I would study in groups too! It makes everything a lot easier and funnier, since more than one is always coming up with weird stuff to memorize things.

I listen to music or change unimportant words in sentences. Ex. original: Bob has 47 lemons but sells 7 how many apples does Jim have. Remake: Donald Trump finds 47 muslims in a room and deports 7 of them how many bullets do i have to shoot him with? See same nonsense problem but more fun.

Thats probably not the best example but i think y'all get the picture.

When you're memorzing words, put gummybears or any other type of candy on very other row. And when you've memorized a new row, you get to eat a gummybear :)

Make it into a drinking game
Take a shot every time you feel like breaking down

@dunkey; This seems counterproductive.

I like walking around the house as I study. Keeps me from going insane.