"Whatever you can do today, don't postpone it to tomorrow" I just learned a German proverb: 


  "Was du heute kannst besorgen, das verschiebe nicht auf morgen," 


which can be translated as:


  "Whatever you can do today, don't postpone it to tomorrow"


Is there a 成语 or 古语 which has the same meaning?  I might use it in the context of encouraging someone to not procrastinate.
&quot;Whatever you can do today, don't postpone it to tomorrow&quot;


This common Chinese saying may had the same origin as the quote in the question:


&quot;今天的事今天做&quot;
&quot;Don't put off till tomorrow what you can do today.&quot;
This phrase is so common, it is in grade school textbooks
variant: 今日事今日做


The idiom 坐言起行 express a similar sentiment in a stronger sense.


&quot;坐言起行&quot;
Once decided, act immediately; When plan is formulated, implement it without delay


There's also a common Chinese expression expressing the similar sentiment


&quot;有花堪折直須折, (莫待無花空折枝)&quot;
&quot;Pick the flower when it is time , (don't wait til there's no flower but stem left to be picked.)&quot;

Original poem:

金縷衣(七言樂府詩)
勸君莫惜金縷衣，勸君惜取少年時。
花開堪折直須折，莫待無花空折枝。
作者: 杜秋娘
Gold Linen Jacket (seven words Yuefu poem)
&quot;You should not cherish gold linen jacket, you should cherish youthful days.&quot;
&quot;Pick flower when it blooms, don't wait til there's no flower but stem left to be picked.&quot;
Author: Du Qiuniang

Side note :
A completely opposite sentiment expressed in another poem is also very famous.
&quot;今朝有酒今朝醉，(明日愁來明日憂)&quot;
&quot;Drink when you have wine today, (worry about tomorrow's problems when tomorrow comes)&quot;
Original poem:

唐·罗隐
得即高歌失即休，多愁多恨亦悠悠。
今朝有酒今朝醉，明日愁来明日愁。