You are a radiation particle of sorts?
My life is so short... too short, indeed.
Radioactive particles can have very short half lives
However, I like using it to help people live better.
Chemotherapy uses radiation to help cancer patients, X Ray's help see things we can't on the surface.
At least, this is what I was made for!
Not sure what is defined as made, because if the roots of radiation are traced back, then we see a rather destructive history, but I guess if we go with the medical side of things, it is produced for good.
Since my countless brothers and I were born, we've been called fat :(
Not sure, maybe the particles are rather spherical and large?
But the satisfaction of opening new doors wherever I go makes up for it!
Cured person is a new person, a new person which opens doors to a new life
Although you can't see us, you would normally find us in a rather spherical geometry. (That's why people say we are fat)
Radioactive particles are spherical
We hate thick obstacles, they make us feel tired!
Thick materials can slow down or completely block radioactive particles
We are a product of engineering advancements, we owe our existence to them.
Engineering advancements allowed for the creation and emission of radioactive particles
I guess they fly?