My preschooler and I often have this conversation:
Pr: " Mom......"
Pr: " I like you."
Mom: " I like you too."
but then, he will at times, then ask,
Pr: "Why do you like me?"
At which time, I will find many things to say to him:
you're a strong superhero
you help save the city
you're nice to your brother
you help clean up your room
you are a great tractor driver
you make have a great laugh
you shared your cookie with me..."
Sometimes I have to think quickly to come up with so many things...but he loves hearing whatever I say and you can see him smile and his head lift a little higher as I compliment him. I think about how great he feels afterwards and try to also do the same to my other children in some way, give at least one compliment a day. There were times (during their teen years) that it was difficult to come up with at least one...but nowadays, it's easy (and worth the time.)