When my boys were newborn, they heard every night at bedtime, "I love you" sealed with a kiss and continued to hear it every night until the day they moved out. When they started to learn how to talk, it warmed my heart to hear them say, "I love you mommy" and as they got a little older it was, "I love you, tthhhhiiiiiisssssss much" with big outstretched arms. As they got older, it was, "I love you too mom".
Whenever my oldest calls or comes over for a visit, he still gets his, "I love you" and I still get my, "I love you too mom".
Now that my youngest has moved back home, I get to say it again every night when he goes to bed, "I love you" and now I get back, "I love you more."