I mean as far as you can without undue stress.就是做你能做到的最大量但不要過度

as far as:遠到...；到 ... 程度

We walked as far as the railroad station.

我們走到火車站那樣遠的地方。

My garden extends as far as the river.

我的花園一直伸展到河邊。

Exercise is thought to reduce the risk of heart attacks鍛煉被認為能減少心臟病的危險

think to:認為

The sea is thought to have been the cradle of life.

人們認為海洋是生命的發源地。

常用短語:come to think of it想一想

It's natural,if you come to think of it.

你要細想一下，就會覺得這是很自然的。

heart attack:心臟病發作

The poor devil had another heart attack last night.

那個可憐的人昨晚心臟病又發作了。

it hard to stick to a punishing gym routine,很難堅持去體育館受折磨的人來說

stick to:堅持

Reporter should stick to investigating the facts.

記者應該堅持調查事實真相。

You'd better stick to your last.

你最好還是做自己分內的事。