My younger brother Scott donated a kidney to my dad a few years ago, both were doing great almost immediately after the procedure. Scott was up walking around hours after the surgery, dad took a few more days, but the kidney functioned just fine. We lost dad to leukemia last February, but the kidney was still going strong right up till the end. It added years onto dad's life. An extremely selfish and unselfish act at the same time - selfish because Scott (and all of us) wanted to keep dad around as long as possible, and unselfish because Scott gave up a kidney to keep dad around as long as possible.
Scott was back to work within 3-4 weeks or so, but he has a desk job, which is not demanding on his body.
I hope all goes well with your aunt.