HI. I donated a kidney 16 years ago, at age 56, by the open-cut method. I had not been very athletic previously, except for long walks, but started doing a little jogging to help in recovery. Then I got enthused to try to get all the way up to 5k (almost impossible) in order to take part in the 5k for donors and recipients at the 2004 Transplant Games in Minneapolis. I did it, and then kept going, all the way up to Marathons. Now at 72 I still do one or two half-marathons a year (slow, a bit over 3 hours) and am in good health.
Some athletic donors do get back to full activity in a month or more, but most seem to take a longer time. No two donors recover the same way. Your hope to get back to normal "in a few days" seems wildly over-optimistic (from the experiences I have read over the years.) You can progress gradually, but it would be wiser to aim for a few months recovery. Some donors do return to very strenuous activity (Iron-Man, weight lifting, etc.), but not right away.
Also keep in mind that not ALL kidney donors recover well. Some have serious long-tern fatigue problems. Some suffer nerve damage. And of course a few have died during or shortly after the surgery. So there ARE risks involved. The many wonderful success stories might give us the impression that ALL donors recover just fine, but that is not the case.
If you post also at the FaceBook page of Living Donors on Line you will get many more responses, and at that site there are both great donor athletes and donors with long-term problems.
This summer, God willing, I will take part in the Transplant Games in Salt Lake City and run the 5k, 1,500 meter and 100 meter. Most of the athletes are recipients, but there are usually 150 -200 living donors there as well. Info at
www.transplantgamesofamerica.org Fr. Pat