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

as far as:远到...；到 ... 程度

We walked as far as the railroad station.

我们走到火车站那样远的地方。

My garden extends as far as the river.

我的花园一直伸展到河边。

Exercise is thought to reduce the risk of heart attacks锻炼被认为能减少心脏病的危险

think to:认为

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

人们认为海洋是生命的发源地。

常用短语:come to think of it想一想

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

你要细想一下，就会觉得这是很自然的。

heart attack:心脏病发作

The poor devil had another heart attack last night.

那个可怜的人昨晚心脏病又发作了。

it hard to stick to a punishing gym routine,很难坚持去体育馆受折磨的人来说

stick to:坚持

Reporter should stick to investigating the facts.

记者应该坚持调查事实真相。

You'd better stick to your last.

你最好还是做自己分内的事。