Those who do not plan for the future will find trouble on their doorstep.

解释 ( paraphrase )
一个人如果没有长远的考虑，就一定会有近期的忧患。
这条谚语告诉我们：平常要有长远的计划和安排，才不会出现近期的忧愁和烦恼。

This proverb advises us to make long-term plans in order to avoid troubles in the near future.

虑：考虑。
      Consideration.

忧：忧愁，忧患。
      Trouble, worry.

造句 ( example )
“人无远虑，必有近忧。”如果我当初做好了计划，现在也不会被领导批评我效率低了。