Word function and back translating '今天难得工作轻松些‘ For me as a non-Chinese, I often find Chinese quite cryptic, which I admire, but that makes it hard for me to get the meaning. Like this morning, looking at this:
（should have written 经历， keyu gan is right)

上班族常常会有这样的经历：今天难得工作轻松些，但是一整天待在办公室里，往往不明原因地感到头晕、心烦，注意力不集中。出现这些情况，往往与办公室噪音有关。

At first I thought: 'Nowadays it is difficult to find and easy job' but then I looked more carefully at what followed and changed my mind. I think it goes like this:

今天  难得  工作  轻松些, 但是 。。。
Today   rare    work    easier, but ...
Today (is one of those) rare easy days at work, but ...
Today (is one of those) rare easier workdays, but ...
Today is / was a rare easier workday, but ....  

I think the structure is:
今天  noun        难得  adjective   工作    noun  轻松些   adjective 

Would you agree?

If I gave you "Today is one of those rare easy days at work," to translate into Chinese, would you arrive at '今天难得工作轻松些，'?

My attempt at back-translating: 今天是一个那种稀有的轻松些的工作日，但是 ....
Congratulations! You got the exact meaning of what the sentence wants to express.

At the very begining, 难得 means hard (难) to come by (得), e.g. 难得的机会 means a chance that is hard to acquire; 这场考试难得高分 means It is difficult to get a high score in this exam. Here, it is an adjective (or a verb), obviously.

Later, 难得 is used to modify a sentence. From my point of view, 今天难得工作轻松些 leaves out the subject 我(I), which should be [(我)今天(难得)工作轻松些] (难得 as an inserted component) / [今天]难得[(我)工作轻松些] (难得 as a sentence adverb). And it can be understood as Today is a rare day when I am easy with work. My opinion can be validated from the point that all the following senetences don't have a subject.

Besides, in the first sentence 上班族常常会有这样的精力, 精力 (spirit, energy) should be 经历 (experience) here. I guess it's a typo.

And it is more natural to say 这些情况往往与办公室噪音有关。 instead of 出现这些情况，往往与办公室噪音有关。