For being so powerful, that phrase is pretty easy to say. There's nothing quite like the first time you're able to say that to someone you've decided you truly care about. But words are cheap.
Real love costs a great deal.
It means that when we love somebody, we choose to be committed to that person. Love is not based on what someone looks like or accomplishes. Certainly we notice those traits, and that can make that person attractive to us. But real love is hard work. A Hollywood producer married a beautiful, much younger woman.