How to not get bored leveling in World of Warcraft?

In WoW, the highest level I've ever got to is 76, because I get bored of leveling very easily. Basically, this is how it goes... I'm questing on my warlock, and see a warrior demolish a boss for a quest that I can't kill, then I want a warrior, so I make one. Then, I see level 85 paladins dueling, and it looks so fun, so I want a paladin. This repeats over and over and over... Anyone have some tips on how to not get bored leveling? Thanks in advance!