I remembered that in Stand Up there was a response from "the only girl in stand-up" to something similar and I will try to reproduce it correctly.
I would like to have a third hand. Imagine how convenient it will be to travel by car. Drive with both hands, and show fuck with the third hand to those guys who think that girls can't drive a car :)
The second heart, obviously. With the condition that the chest will be slightly expanded (I also want the same lung volume as with one heart). Increased endurance (cardio loads will be given many times easier, therefore, it will be easier to develop muscles). The load on each of the hearts will be less, therefore, the service life will be lengthened. Well, I also have "one extra life" in case of illness of one of the hearts or a serious injury, for example. True, in this case, you should beware of injuries to the artery, because the heartbeat will be twice as often, therefore, the blood will flow faster.
Naturally, this idea was inspired by Doctor Who and the Space Marines from Warhammer 40k
P.S. Where does this cutest creature in the picture come from? Some kind of a mixture of Pokemon and Homo-homo Zek from One-Punchman
I would like a third lung between the two existing ones. A kind of 3rd filter. For our ecology is poor. We will all need extra lungs soon.