Depends. As one of our few paired organs, kidneys were i believe the first used in living donor transplants.Affect on lifestyle depends on your circumstances.I'd encourage a horseman or bull rider to stop, or quit playing sports where you are most likely to take a good hit & could injure the remaining one.If this doesn't describe your liifestyle, it likely wouldn't affect it. You only need one to live well.
Should not. Unless you race motor cycles or practice extreme sports, in which case those should be curtailed. Your kidneys are very well protected within body. Kidney injuries are few and far between + most respond to conservative measures like rest. Thus sports such as football, ice-hockey, soccer, baseball, basketball etc. Are all ok. You will be saving a life if and when u donate. Please do.