Walk like a big boy

I saw a Mum with her son, he was about 8 years old. He was walking next to her while clinging on to her hand and arm. She shoved him away, release his grip on her hand and said:
"Walk like a big boy"

He whined a little bit but agreed - all I could think was:
"In less than a year he won't ever want to hold you hand again - maybe you should take advantage of the moment?"

I don't know, maybe some people aren't sentimental...