Saying is not the same as doing. Inherently, this is an obvious statement. But when it comes to the application of this truth, it is often overlooked.
In a practical sense, I learn a new card game much more quickly and with more ease when I'm given the cards and told to play, rather than read a set of rules. In painting and sculpture, I can sit and learn theory day in and day out and still not know how to paint a masterpiece. These instructions, these words do help; I cannot make up any rules I like for the card game that I'm playing, I have to follow those that make the game what it is. My painting will be better, from a critical sense, if I know about balance and composition. In life, just as in card games or art, you cannot remain ignorant of the rules, but refusing to follow them is just as bad.
I can say, "Yes, Mom, I will clean my room" until I am blue in the face, but if I do not clean my room, what are those words worth? What did they mean? What purpose did they serve but to mislead my mother into thinking I would obey? Those words were worthless. They meant nothing because I, in fact, did not clean my room. My words were a lie. Perhaps not intentionally, but they were a lie nonetheless. It follows then, that the simple phrase "I love you" is worthless. It means absolutely nothing if it is not followed up upon. "I love you" is a lie.
That is, unless there are actions present that give the words truth. I washed your car for you, I kissed you, I called you just to chat, I made you hot cocoa when you were stressed, I took time out of my day to care for you. Suddenly, "I love you" means something now. It is clear that I do indeed love you because I've done all these things for you. I simply didn't say it and walk away. My words now mean something. They have worth. They are truth.
Ralph Waldo Emerson once said, "What you do speaks so loud that I cannot hear what you say." Our words, what we say, are far out-shadowed by the things that we do, the actions that we take. The next time you feel like telling someone "I love you", hold your tongue and think of what you could do that would communicate your love to them. Act. And in this, perhaps find truth.