Usually, it's not a good practice to re-post lyrics that are already in the Digital Tradition. The suggested practice is to provide a link or to tell people how to search the database (after making sure the song actually is in the database). There are times when I question that policy, because posting the lyrics can generate a nice discussion, like this on.
Gene's comment spurred me to look up the history of the song in Sing Your Heart Out, Country Boy (Dorothy Horstman, 1996).
Here's what songwriter Scott Wiseman says about the song, which he wrote in 1945:

I was a patient in Wesley Memorial Hospital in Chicago for several weeks in 1944. My wife, Lulu Belle, was visiting me one afternoon and whispered to me before she left, `Have I told you lately that I love you?' As I lay there thinking tender thoughts about her, it occurred to me that this would be a good title for a song. I got paper and pencil and wrote the first verse and chorus down that afternoon. When Lu came the next day, I sang it to her. She said, `That's pretty good.' A friend of mine took a copy to Gene Autry in Hollywood. He made the first recording. Lu and I still get a thrill when we hear it done by so many fine artists, and it paid for our retirement home in the hills of North Carolina. It has sold approximately 10 million records here and abroad.

-Joe Offer-