There's no specific phrase for that in english. Sometimes we say"good job/good work" Or "sounds hard" or something. Or simply "dang/wow" "I just got finished my homework" "Good job" I just got off work Nice. I just worked 12 hours. Dang. That sounds hard 我们比较随便。这个句子不好翻译。

Maybe make a not of the differences in British and American English here too, dang would not be said by someone from the UK. So perhaps it could be expressed as: "Damn, that's hard."

Maybe you can say "take it easy". I think “辛苦了” just a regard, but to say "take it easy", you give him a suggestion for how to release his “辛苦”.

"Woe is me." woe is me old use or humorous › said to express how unhappy you are: I'm cold and wet and I haven't even got enough money for my bus fare home. Oh woe is me! Translations of “woe is me” in Chinese (Simplified) 苦啊, 惨哪… http://dictionary.cambridge.org/us/dictionary/british/woe-is-me#translations

I think it depends. cause the different culture, i don't know any perfect translation for that. but maybe i would say: You did a great job! if you want to cheer someone up. You had a hard time! to show your understanding and pity. :P