Why can't it be a combination of both?
If you want to recover from wounds, you'll need the mental power and recilience to do so. Placebo's proof this.
Padme might have been mortally wounded, but with good chances to survive. But if the mind doesn't want to do so...it won't work.
Although I still find it weird she doesn't stuff it away to raise the children. I mean, what's the point? She leaves the children mother and fatherless.