It's been more than 15 years since I heard this beautiful country music. The song tells us the story of a man (or a lady) that gets in trouble by having a flat tire that they can't repair, then some guy stops by and helps and when the driver offers money for the service, the guy refuses and says something like "I have been where you are, I needed help and someone helped me and told me to pass that help". And thus, the drivers moves on to a diner and has something to eat, and when the waitress came to collect the payment, she finds an extra 100 dollars, or something like that.
We later find out that the waitress is the wife of the guy who fixed the tire. So, in a way, the help has made a circle.