Love is NOT the puppy thing it shows on TV.
Love is waking up next to that person everyday, going to work, coming home, making dinner, cleaning. Sharing in each other's joys and pains, being there for one another.
Love is just the thought of that person crossing your mind, and it makes you smile, no matter how bad the day is. And when you smile at the thought of them, you realize that the day can't really be that bad because you get to go home to them.
Love is not flowers and candy everyday, but rather the little goofy moments you share together that are worth more than ten thousand bouquets of roses and boxes of candy.
Love is not always having the pretty words that sweep you off your feet, but rather trying to say something that even comes close to how you feel. And realizing that these pitiful words that you give are better than if you had the most eloquent words in the world at your disposal.
There is no explanation to know when you love someone, you just do and you'll know when you do. And you'll know that this is the real thing, and the other feelings you had were just a pale brief shadow of the real thing. And you'll know that the word 'love' is not strong enough. That there is no word strong enough. But 'love' is the only word you've got, so you use it to the point of wearing it out.