Fetching details from the dictionary...

unreasonable; unnatural; unjustifiable
impossible
forcible; forced; compulsory
excessive (work, etc.); immoderate
to work too hard; to try too hard
no way; not a chance; never; dream on
irrational
無理をしないでくださいね。
Please don't push yourself.
今日中に終わるのは無理だ。
It's impossible to finish today.
無理なお願いをしてすみません。
Sorry for the unreasonable request.