person A: Today I was getting coffee and the person in front of me paid for my drink. I couldn't believe people would be so nice_comma_ I was so thankful because money has been tight.
person B: How thoughtful.  Now you have to pay it forward_comma_ as the saying goes.
person A: I will_comma_ you never know when someone else is in need! 
person B: Kindness is infectious.
person A: It is_comma_ I have been so blessed in my life! 