Shopping After A Night Shift

I don't know what with shopping that even after a 3 night shifts I can still stay awake the whole day. But compared to my friend J. she is so much better on this. Imagine we went together to the city after her 7th night shifts. No complained of back pain, joint pain and whatsoever. And she's been doing it for years now. She is around 8 years older than me but no slowing down. I hope I can survive this nursing job until my kids graduated from university. This will be another 15-20 years from now. This made me shout you know. Waaaaaa!