I was in the newsagent buying some PVA glue this morning, when I realised I didn't have any cash on me - and this lovely young guy says "let me get that for you". He was shocked himself that words had come out of his mouth, said he felt like doing something nice for someone.
It has left me with a real spring in my step, such a nice gesture. And I will absolutely pay it forward all day. Thanks Mr Nice Guy.