Whether it's to avoid work or escape physical activity, we've all had those days.

無論是不去工作或是偷懶不運動，我們都經歷過這些。

But why are some people way lazier than others?

但為什麼有些人就是比其他人懶呢？

Is there a couch potato gene that causes lazy behavior?

難道有種沙發馬鈴薯基因會導致懶惰行為嗎？

Evolution has molded our brains and bodies to respond positively to natural rewards, such as food, sex and even exercise.

演化造就了我們現在的大腦以及身體，用以正向回應那些自然的報酬，像是食物，性愛，甚至運動。

Wait, exercise?

慢著，運動？

Yep, the pleasure we experience comes largely from the dopamine system in our brain, which conveys these messages throughout the body, ultimately helping to ensure the survival of our species.

沒錯，我們所體驗到的喜悅大部分都來自腦內的多巴胺系統，它傳送訊息到全身的各個角落，確保我們這個物種的存續。

For many, the pleasure derived from exercise can become just as addictive as food and sex.

對很多人來說，他們從運動所獲得的喜悅可能跟食物以及性愛一樣地令人上癮。

But while we're all up for more food and sex, many struggle with the desire for physical activity, even though it's an essential part of human biology.

但儘管我們都喜愛食物與性愛，卻有很多人不太喜歡運動，就算運動也是人類生物習慣中重要的一環。

Scientists studying mice have found an interesting genetic connection.

研究老鼠的科學家們發現了一個有趣的基因關連性。

After separating mice into two groups, those that chose to run on their wheel more often and those that decided not to run as much, the difference was clear in their offspring.

把老鼠分成兩個群體，一群比較喜歡在滾輪上跑步，另一群則沒那麼常跑步。兩者的差異明顯地反應在了牠們的後代身上。

After ten generations, the running mice would run on their wheels 75% more often than the other group.

經過十代之後，常跑步的老鼠群跑步頻率會比另一群多上 75%。

And by 16 generations, they were running seven miles a day as opposed to the average four miles.

而在經過十六代之後，相較於一般老鼠一天平均四公里的跑步距離，常跑步的那群老鼠後代能跑上七公里。

It seemed their motivation for physical activity was genetic.

牠們對於運動的行動力似乎是來自基因。

We all inherit genes from our parents that play a key role in the development of our brains, and these genes can make some literally crave activity.

我們身上都帶著來自父母的基因，而這些基因在大腦發展過程中有著關鍵作用。

In fact, the brains of the running mice had larger dopamine systems and regions that deal with motivation and reward.

事實上，那些愛跑步的老鼠大腦裡，處理行動力及報酬的多巴胺系統與區塊比較大。

They needed activity, otherwise their brains would react similar to a drug addicted rodent when deprived of cocaine or nicotine.

他們需要運動，否則他們的大腦會發出和藥物成癮後，被剝奪古柯鹼或尼古丁的齧齒類動物相似反應。

They were genetically addicted to running.

牠們在基因上就已經對跑步上了癮。

We also inherit genes responsible for our other traits from impulsivity to procrastination to work ethic and straight up laziness.

我們也會傳承那些決定我們特質的基因，包含衝動、拖延、工作倫理，或是懶惰程度。

And it turns out our physical laziness may be linked to a "couch potato" gene.

並且看來生理上的懶惰，可能跟「沙發馬鈴薯基因」有關。

Or rather, a mutation in a normal gene which regulates activity levels.

或者說，與調整運動量的基因發生的突變有關。

This gene is responsible for a type of dopamine receptor.

這種基因負責控制一種多巴胺接受器。

Without it, you're more likely to prefer sitting around and simply doing less than those who have the properly functioning gene.

要是少了這個基因，你就較可能喜歡閒閒坐著，勞動的量也會比那些基因正常的人少。

So the truth is your desire for activity may not entirely up to you.

所以真相就是，你對於運動的渴望可能不全然由你決定。

But many environmental factors are also at play, which means you aren't doomed to a life of laziness.

但還是有許多環境因素參雜其中，也就是說你不是注定要過上一段懶惰的人生。

Although making a change will be harder for some, knowledge is power!

也許對於某些人來說，改變是件困難的事，但是知識就是力量！

So if you think you're genetically lazy, get off the couch and fight your DNA.

如果你認為是你的基因使你懶惰，那就離開沙發，並對抗你的 DNA。

Your brain will reward you in the end.

你的大腦最終會給予你回報。

Need some help to get there?

需要達成目標的幫助嗎？

Check out our past video on the science of productivity, which might help you improve your motivation and fight that laziness.

看看我們之前的影片 — 生產力的科學，可能可以幫助改善你的行動力並對抗懶惰。

And if you'd like to learn more about the amazing science behind extraordinary athletic performance, check out one of our favorite books

想知道更多有關非凡運動員表現背後的科學知識嗎？來看看我們最愛其中一本著作，

The Sports Gene by David Epstein, which was a major source for this episode.

由 David Epstein 所寫的「運動基因」，也是這一集主要的資料來源。

It's a great read and you can get a copy of it using the link in the description below.

這是本優質讀物，你可以透過下面資訊欄的連結來取得這本書。

And subscribe for more weekly science videos.

別忘了訂閱頻道，觀看更多的每週科學影片！