This is it! We’re doomed! They won’t be coming to the door with big guns to try and kill us! No, they’ll be creepy little monsters, lying in wait for their opportunity to get inside our bodies and then make their way to our brains, where they’ll start hacking away with their little micro-knives and scythes! Aaack!
What I want is nanobots advanced enough to destroy all pathogenic organisms, fix my vision to 20/5, tone my muscles automatically, prevent deterioration of brain cells and roll back my body’s age to a permanent 18.
Doubt such a thing will be possible before I die of old age though.