Not from my brain but a book discussing phrases like this -->
ichinichi mo hayai gokaifuku o inotte orimasu.
I hope you get well soon
一日も早いご回復を祈っております。
It was suggested as a suitable farewell when visiting someone who is ill.
(お大事になさってください
odaijini nasatte kudasai
Please take good care of yourself
was an alternative.
I'm sure I've heard this contracted to odaijini Take Care)
and found something similar in EIJIRO
速やかなご回復を願っております : I hope that you have a speedy recovery.
the example you give I think would be
hayaku yoku nare
はやく よく なれ
なれ being the imperative of なる. to become
isn't that a bit abrupt in Japanese terms? Get well soon (or else you slacker!

)