[U3] Use of English3

The person who comes up with the answer as to how to live a long and happy life make a fortune.
come up with answer / plan / idea / think / suggestion / theory ...
このas toはrefer to/with reference toの意味かな？？

Until that happens, scientists, life coaches and fitness fanatics are all free to put forward their own pet theories.
put forward : pet theory / project / subject ...

Leaving aside the wackiest ideas, their suggestions all seem equally plausible and could well play an important role in uncovering the truth about longevity.
longevityの発音

Follow this diet, exercise, surround yourself with people who love you, sleep long hours - these are all sensible things to do, and indeed could lead to a longer life span.
surround oneself with

But something gets in the way of our doing them, and trying to follow advice and failing creates stress, which has a really negative impact on our sense of well-being.
get in the way of / a sense of well-being

People are put off by things that challenge them, and this includes the apparent impossibility of achieving a perfect lifestyle.

To many it seems an unattainable goal that is out of reach. [..]

質問されたり似たような選択肢を示されると迷いが出る。で、考えすぎて間違う。なので「完璧に」覚えないといけない。
言いたいことが伝わればいいというビジネス英語では全く太刀打ちできない。Use of English