system
grateful: 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, I was so thankful because money has been tight. 
gpt
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, I was so thankful because money has been tight.
human
How thoughtful.  Now you have to pay it forward, as the saying goes.
gpt
I will, you never know when someone else is in need! 
human
Kindness is infectious.
gpt
It is, I have been so blessed in my life! 