我们的身体和大脑之所以会有这么强大的适应能力，恰恰是因为我们的身体有一种偏爱稳定性的倾向。这句话初读来有点不可思议，但是仔细一想，也不难理解。

书中举例有氧运动，比如持续性的慢跑，会使得供应腿部肌肉的毛细血管的氧含量降低，于是我们的身体会通过生长新的毛细血管来为腿部肌肉提供更多的氧气，从而使我们的双腿重新回到“舒适状态”。

The sustained activity will, among other things, lead to low levels of oxygen in the capillaries that supply your leg muscles. Your body will respond by growing new capillaries in order to provide more oxygen to the muscle cells in your legs and return them to their comfort zone. 

我们都有过这样的经验，很长时间没有运动了，忽然间跑个步爬个山啥的，第二天就会全身酸疼各种不适，可若我们坚持有周期性的跑步或者爬山，一段时间后，当我们的身体适应并重新达到平衡（Homeostasis）后，我们就会觉得“这都不算事儿”。

同理，周期性的训练会使我们的大脑中受到训练挑战的区域发生改变，通常是变大（例如前面提到的伦敦出租车司机的海马体实验研究）。

Regular training leads to changes in the parts of the brain that are challenged by the training.

鉴于大脑的复杂性，在训练大脑时有三个重要细节值得注意：

• 折弯幼枝效应（the bent-twig effect）：我们都明白，刚长出来的幼枝相对于已经长成的枝条，更易被折弯而改变长向；而我们的大脑也会因年龄越小，适应能力越强，也就越容易被塑造；

  
  

• “此消彼长”原理：大脑的某些部位因受训而变大增强，随之也会影响其他区域的功能，所以说，“上帝总是公平的”；

• “不用则退”原理：因受训而获得认知和生理变化的大脑区域，需要保持训练，一旦停止，就会开始消失。

我们的身体会适应改变而重新达到“体内平衡”（Homeostasis），而我们的大脑也会 “不用则退”，因此我们若想进一步提升自己，就要挑战我们的体内平衡，走出“舒适区”，迫使我们的身体或大脑来适应新的变化，只有这样我们才能发掘并构筑自己的潜力。

This requires challenging homeostasis—getting out of your comfort zone—and forcing your brain or your body to adapt. 

那么问题来了，我们要挑战体内平衡，开发大脑潜力的最佳方式是什么呢？期待接下来的阅读。。。

Thus, the body is equipped with various feedback mechanisms that axt to maintain the status quo.

status quo, 名词，意思是“现状”，[singular]: the current situation : the way things are now. 常见搭配有：maintain/preserve/defend the status quo (=not make any changes). 

延伸知识点：行为经济学上有个 status quo bias (维持现状偏见)，指的是：人在作决策的时候会把现状作为基准，而任何改变都会被当成是一种损失，因而会倾向于维持现状。比如，我们会选择熟悉的食物，熟悉的品牌等；

例句：He is content with the status quo and does not like change.

仿造句：If you want to change your status quo, you have to get ouside your comfort zone.

If you don't keep pushing and pushing and pushing some more, the body will settle into homeostasis, albeit at a different level than before, and you will stop improving.

albeit, 连接词，used to add information that reduces the force or importance of what you have just said，表示“即使，虽然”，可替换词：even though、although.

例句：He accepted the job, albeit with some hesitation.

仿造句：She has decided to quit the job, albeit her parents disagree.

The training of a London taxi driver or an Olympic gymnast or a violinist at a music academy is, in essence, a method of harnessing the adaptability of the brain and body to develop abilities that would otherwise be out of reach.

in essence, 副词，表示“本质上，其实，大体上”，used when talking about the most basic and important part of something, especially an idea, belief, or argument; 可替换词：basically、essentially、fundamentally.

例句：He was in essence [=basically, essentially, fundamentally] an honest person.

仿造句：It is, in essence, a win-win result for both of them.

对比学习：be of the essence，形容词，表示“极其重要的”: of the greatest importance.

例句：Time/speed is of the essence when dealing with a medical emergency.

A second detail worthing noting is that developing certain parts of the brain through prolonged training can come at a cost: ...

学习一个写作表达，a second detail worthing noting is... 第二个值得注意的细节是... detail 可以替换成其他的词，如 idea, part, point...etc.