I remember an old man in a health care program suggested a way to strengthen the kidney, that is, rubbing his back with his palm every day, but now he can't find it.
I know one. I don't know if I'm talking to you. First, I rub my hands in pairs, press my waist and eyes tightly, pause for a moment, and then rub down to the tail (Changqiang point). Do it 50 ~ 100 times each time, once in the morning and once in the evening. But the old man you mentioned, I don't know. I hope the above can help you.