"In My Life" is a Beatles song, written by John Lennon and Paul McCartney, with John Lennon being the principal author and Paul McCartney assisting him. The song was included on 1965's Rubber Soul album. This song is an example of The Beatles middle period, when their subject matter was becoming more experimental and introspective, but was still written in recognizable pop music format.
The song is soft and melodic, with a theme of nostalgia. I don't really have the technical knowledge to explain why, but the music quickly and perfectly captures the mood of nostalgia. The lyrics are fairly spare, but are again perfect for conveying the nostalgic feeling.
So what is interesting about the song is after the first verse captures this mood, the second verse seems to move on, with John Lennon talking about finding new love, and saying that although he will "always have affection" for his past, it fades in comparison to the new love he has discovered.
There is a reason why John Lennon is considered one of the most creative song writers of the 20th Century. His songs can often do many things at once. From the lyrics of this song, we are hearing a man think about his past, and then look to his future. He is "Thinking of love as something new". But the melody of the song is very wistful, even sad. The song is about nostalgia, and the past. The feeling of the song does not speak to finding a new love, and thinking of the future.
Which is not to say that the song is being deceptive or lying. Even if we do accept my impression, its hard to "lie" in a song. I think that the answer is more complicated, that the song is talking about how new things can not be appreciated without old things, that happiness can not be appreciated without loss, and that the greatest love can not be appreciated without the smallest affections that make us who we are. Which is quite a lot to get across in a song that is only two and a half minutes, but that is why The Beatles are considered to be the greatest rock band of all time.