Como dizer "É preciso se esforçar muito" em inglês

"É preciso se esforçar muito pra isso." (In an ironic way) = "That takes some doing."

For instance:
"Twice in one emergency shift, I missed appendicitis. Now that takes some doing!"
"Eu já deixei passar dois casos de apendicite num único turno. É preciso se esforcar muito pra isso!"

Source: TED talk ("Doctors make mistakes. Can we talk about that?") (at 11:03):
Link to the original video: http://www.ted.com/talks/brian_goldman_ ... _that.html


Pay attention, though, that, different than Portuguese, the expression "to take some doing" can be used in a non ironic way too.

For instance:
"It took some doing, but I finally got the manager to agree to hire you." - Source: http://idioms.thefreedictionary.com/take+some+doing

By the way, I highly recomend you to watch that entire talk. It is one of the best I have ever seen on TED.

Hope it helps.