I had my left kidney removed when I was sixteen years old due to it's being ruptured in a bicycle accident.
I am now 78 years old and I have never had any trouble with my right kidney. Of course I don't know why your left kidney is giving you trouble and if your right kidney is healthy, but if it is I would encourage you to have the surgery. I don't think ordinarily that surgery is the best answer for health problems. But that's life. We have to choose what's best for us and forget perfectionism. Alternative medicine is after all not a religion.
I worked for forty some odd years as an electrician, did some heavy llifting at times, ran several miles a day when I was in my fifties too. So I have not felt I needed to forgo any activity. Good luck Amigo