"Firebending power comes from the breath, not the muscle."

Wheezes in asthma

I’ll have a think before I give my full answer, but what I will say is that these do not enhance their respective elements. Toph’s blindness enabled her to learn to feel the earth better, but in theory an earthbender could be just as good as feeling the earth. Also, not having arms did not enhance Min-Hua, it hindered her. She was a great waterbender, but with arms she would have been much much better. She was unique, but not necessarily enhanced.

Blindness makes her better. Without it, she would not have learned from badgermoles, and she would not use neutrual jin, the best earthbending tactic. Also, it makes people underestimate her. I have not finished Korra yet, so I don't know who Min-Hua is, but I'm guessing something of the same nature applies to her. As for airbending, I'd say that paralyzed boy with the glider would make a good airbender... it would mean that that kid couldn't solve everything with brute force, which is the very essence of airbending. But, airbending also is freedom, so they'd have to be paralyzed only partly. Firebending comes from breath, huh? Maybe not literally, but I remember Zuko saying that Firebending was about emotion, and if someone was mute, they would take out their emotions through firebending.

If waterbending comes from feeling the flow of energy through your body, then I would imagine that clogged arteries would hinder your flow. So would constipation. Just a thought...