Lyrics With Life Advice

I was chatting on FB with several friends about song lyrics that we’ve absorbed as life advice.  I always lean towards inappropriately timed humor, like singing Ringo Starr’s “No No Song” when my child had temper tantrums.  I’m capable of being serious, though.  Many of my deep life beliefs are summarized in a lyric.

How about you?  What lyrics make great advice?