I found out that I had a solitary kidney in 2006 during a PET scan prior to beginning chemotherapy for breast cancer. I was 58. Until I hit my 40s, I was active and relatively healthy. Then I started a new job and then a business which consumed every waking moment until I was diagnosed with breast cancer. At 71, I have this that and the other in addition to all the fun stuff that seems to comes along with aging and being a stage IIIB cancer survivor. (13 years now!)
Living with a single kidney hasn’t been responsible for any of my deficits so far. I am careful to keep well hydrated and don’t drink alcohol. Those are the only things I do to keep my kidney as healthy as possible. So go for it! In addition to being active, I had 2 sons well before I knew I had only 1 kidney.
I think what I’m trying to say is that you can live quite normally with 1 kidney. All the best...