When you spend all your spare time in and at school and or work trying to bend.

When in dance class instead of dancing you are secretly spying on the enemy and trying to incorporate their difficult moves into your bending you are trying to do.

When you have seen every episode of Avatar at least thirty times.

When you spend your time at school when your supposed to be doing homework you are actually online doing something Avatar.

When instead of listening to your teachers lectures you are doodling the four symbols on every piece of paper you can reach.

If when season three started you drew the water symbol on one cheek, air on the other, fire on one hand and earth on the last hand.

Every dream you have includes Avatar in one way or another.

Your brothers and parents begin to call you overly obsessive.

Your screen saver changes to a new Avatar picture every day to try to get all of them at least once.

You have written fanfiction during the wait for season three because you just couldn't get enough.

When that fanfiction is still on your computer seven months later and you still just love to read it.

(And yes I have done every single thing listed above, and more)