More than words is all you have to do to make it real
A depthy post on the nature of love is far beyond the scope of this blog (and let's face it, far beyond my comprehension). But I will say this: I think it's very easy for us to offer the words "I love you" as just that - an offering; a gift. We often say it in the same way we would give a compliment; a sort of kind gesture from me to you. The gift I give is the way I feel about you. This is not to say that the backing sentiment is phony, but simply that we don't always take pains for our meanings.
The sages of our time often inform us that love has more to do with our actions than our emotions, and while that sounds all noble and good, the thing is that it seems to actually, quite literally be true.
Exhibit A: Some time ago I began to feel uneasy whenever I got to that part in my prayers when I told the Lord that I "loved Him." My subconscious understanding of love being a gift rendered my declaration immediately ridiculous. Who am I to think that I have anything to give that He doesn't already have? The implication of gift-giving is that one must have and one must lack, and this is never the case in our relationship with the Omnipotent God. Even more disturbing, if love is simply a way of feeling about someone, who am I to "feel" towards the Lord as a man feels towards his pet dog, or the mountains, or Beethoven symphonies? The notion implies a sort of evaluation I have over some sort of raw material. To assume that I have any sort of capacity for evaluating the Lord is probably the most outrageous and offensive thing ever.
But alas, the saving grace lies in the fact that I was wrong about love. It is not a gift you give by saying it. It is an explanation for something you're already doing. Ideally, when I tell you I love you, it is a pleasant but unnecessary caption for the illustration of everything I am doing to support, nurture, and care for you. And you see, when we look at it this way, it makes perfect sense to tell the Lord we love Him. We are not so much expressing a sentiment to Him as we are committing ourselves to continue serving him; to act in charity towards Him and all men, because charity is the pure love of Christ.