Rapidly or speedy.
The adverb form is "quickly." *In some cases, as with "fast" the word quick may appear instead of quickly, e.g "Come quick" instead of "Come quickly."
Instead of using the word challenging you can use the word gifted, special, special gifted.
Will, when, why, it, can
or
He answered the question quickly and accurately.
Myself
I have a stomach ache.
mixture
are
She quickly changed her wig before the cops arrived.
It could be used like... "The penguin's short legs didn't allow him to run quickly, so instead he moved with a funny waddle."
used to be