經濟學家教你如何堅持去健身房

If you’re like a lot of Americans, one of your New Year’s resolutions is to work out more. If you’re like a lot of Americans, you’ll join a gym this January as part of that plan. And if you’re like a lot of Americans, you won’t go very much.
你是不是和很多美國人一樣，新年規劃之一是要多鍛鍊，並在今年1月爲此辦了一張健身卡，但實際上卻不會常去？

Our overoptimism about how much we will work out has been the subject of academic research. Nearly a decade ago, the economists Stefano DellaVigna and Ulrike Malmendier published “Paying Not to Go to the Gym,” a paper in which they found that members at three Boston gyms went an average of 4.3 times a month. With monthly membership fees of just over $70, that meant an average of $17 per visit — well above the $10 charge to work out as a nonmember.
關於我們對自己會進行多少鍛鍊過分樂觀的問題，一直是學術研究的對象。近10年前，經濟學者斯特凡諾·德拉維尼亞(Stefano DellaVigna)和烏爾麗克·馬爾門迪爾(Ulrike Malmendier)發表了一篇名爲《付了錢卻不去健身》(Paying Not to Go to the Gym)的文章。他們在研究中發現，波士頓三家健身房的會員平均每月去4.3次。在月會員費略高於70美元（約合440元人民幣）的情況下，這意味着每去一次平均花費17美元，遠高於非會員鍛鍊一次10美元的收費。

So why didn’t they just pay per visit? Because they overestimated how often they would go. The authors surveyed gym members who, on average, said they would work out about 9.5 times a month, more than twice the actual attendance observed in the study. People remained in denial about their gym attendance even after they’d stopped going entirely: On average, nonattending gym members did not cancel until 2.3 months after their last visit, paying for $187 worth of completely unused gym access.
那麼，他們爲什麼不每次單獨交錢呢？因爲他們高估了自己去健身的頻率。文章作者對健身房會員做了一項調查。受訪者希望平均每月鍛鍊9.5次，是研究中觀察到的實際次數的兩倍多。甚至在徹底不去了以後，人們也依然不願承認自己去健身房的實際頻率。不再去的人註銷會員資格的時間，與他們最後一次去平均相隔2.3個月，也就是說他們花187美元買的服務根本沒用過。

Lightly used gym memberships aren’t limited to Boston. The last annual shareholder filing from Town Sports International, the parent company of New York Sports Clubs, showed the company had 497,000 members making 29.1 million annual visits; that is, the average member visited five times a month.
健身房會員資格利用不充分的情況並不僅限於波士頓。紐約運動俱樂部(New York Sports Clubs)的母公司城鎮運動國際(Town Sports International)最新的一份年度股東備案文件顯示，公司有49.7萬名會員，全年的健身人次是2910萬，即平均每名會員每月去五次。

Since pay-now, work out-later isn’t working as a strategy, economists have been searching for other solutions to get people into the gym more often.
由於“現在付錢、以後鍛鍊”的策略不起作用，經濟學家們一直在尋找其他解決方案，以提高人們去健身房的頻率。

“We describe a field experiment measuring the impact of bundling instantly gratifying but guilt-inducing ‘want’ experiences (enjoying page-turner audiobooks) with valuable ‘should’ behaviors providing delayed rewards (exercising),” wrote the economists Katherine Milkman, Julia Minson and Kevin Volpp of Wharton in a 2013 research paper. They gave Penn undergraduates free iPods loaded with audiobooks of their choice, but told them they could listen to them only at the gym.
“我們描述的是一項實地試驗，衡量將‘想做’的事情和‘應該做’的事情結合在一起的效應。‘想做’的是當時令人高興但卻會引起內疚的事情（聽引人入勝的有聲讀物），而‘應該做’的是有價值且會在日後帶來回饋的事情（鍛鍊），”沃頓商學院的經濟學者凱瑟琳·米爾克曼(Katherine Milkman)、朱莉婭·明森(Julia Minson)和凱文·沃爾普(Kevin Volpp)在2013年的一篇研究論文中寫道。他們給賓夕法尼亞大學的本科生提供免費的iPod，裏面有學生自己選擇的有聲讀物，但又要求學生，只能在健身房裏聽。

This worked for a while: The undergrads given the iPods went to the gym about 50 percent more often than others who were just given a Barnes & Noble gift card to spend as they pleased. (A third group, given a book iPod to take home but encouraged to listen only at the gym, placed in between the other two.) But that lasted for about seven weeks. Thanksgiving break came, and the students returned to school having fallen out of love with their audiobooks; they no longer worked out more than their peers in the control group.
這個辦法一度奏效：得到了iPod的本科生去健身房的頻率，比只拿到了巴諾書店(Barnes & Noble)禮品卡且可以自行決定其用途的學生高出了大約50%。（還有一個小組的學生也得到了有聲讀物。研究人員讓他們把有聲讀物存在自己家裏的iPod上，但鼓勵他們只在健身房聽。這組學生去健身房的頻率介於另外兩組之間。）但這種情況只持續了大約七週。感恩節假期結束後，返校的學生已經不再受到有聲讀物的誘惑，鍛鍊的頻率也不再高於控制組的成員。

“It was a bummer from the perspective that we’d like to design interventions that work forever,” said Ms. Milkman. But she also noted that there are lots of opportunities to try again. Gym visits don’t just pick up at New Year’s but at the start of each week, each semester, after holidays, and even after birthdays (though not 21st birthdays). The key is getting one of the fresh starts to stick.
“從我們希望設計永久有效的干預這個角度來說，這種結果令人失望，”米爾克曼說。不過她也指出，有很多重新嘗試的機會。去健身房的人次增加不僅出現在新年伊始，也出現在每週和每學期開始的時候，以及節假日甚至生日（但並不包括達到合法飲酒年齡的那個生日）過後。關鍵是讓其中一種堅持下去。

Heather Royer, an economist at the University of California, Santa Barbara, thinks she has hit on a way. In partnership with a Fortune 500 company, she and her research partners ran an experiment that combined two interventions: One to get people to start going to the gym, and another to keep them there. For four weeks, the company paid its employees to work out, $10 per visit up to three times a week. After those four weeks, there were no more payments, but some workers were offered a “commitment contract”: They could set aside their own money that would be released to them only if they worked out over the next two months; otherwise, it would be given away to charity.
加州大學聖巴巴拉分校(University of California, Santa Barbara)的經濟學者希瑟·羅耶(Heather Royer)認爲自己發現了一種方法。她和研究夥伴與一家財富500強(Fortune 500)公司合作，進行了一項實驗，將兩種干預結合起來：一種是讓人們開始去健身，另一種是讓他們堅持下去。在四周的時間裏，這家公司出錢讓員工去鍛鍊，每次獎勵10美元，一週最多三次。四周過後，公司不再發錢，但部分員工簽署了一份“承諾合約”：他們自己留出一部分錢，接下來兩個月如果堅持鍛鍊，就會還給他們；如果沒能堅持鍛鍊，這些錢將被捐給慈善機構。

Even though those commitment contracts ended three months after the start of the study, the effects on workout frequency persisted for years: Three years after the study, the workers who had been offered the contracts remained 20 percent more likely to work out than those who had not been offered any incentives. By inducing a habit with cash payments, and then reinforcing that habit with self-funded payments, the researchers were able to permanently change workout habits for at least some people.
儘管這類承諾合約在研究開始三個月後就到期了，但它們對鍛鍊頻率的影響卻持續了多年：研究項目過去三年後，當初簽署合約的員工健身的機率，依然比那些什麼激勵都沒得到的人高20%。通過用現金獎勵的方式培養一種習慣，然後再用自己出錢的方式來鞏固習慣，研究人員永久性地改變了至少部分人的鍛鍊習慣。

The researchers at Wharton also found demand for continuing self-control devices: After study completion, 61 percent of subjects said they’d be willing to pay for gym-only audio books as a measure to help themselves work out.
沃頓商學院的研究人員還發現，需要有持續性的自我控制策略：研究結束後，61%的實驗對象表示願意出錢購買只能在健身房聽的有聲讀物，以此作爲促進他們鍛鍊的手段。

So why don’t gyms offer these kinds of devices to drive members to work out more?
那麼，健身房爲何不提供這類措施，促使會員多鍛鍊呢？

“They have a little bit of a conflict of interest,” says Richard Thaler, a behavioral economist at the University of Chicago. The fact that lots of people join gyms and rarely go to them isn’t great for our national waistline, but it’s pretty good for people who own gyms. “If they succeeded in getting people to go to the gym three times a week instead of three times a month, they wouldn’t be able to have as many members.”
“這裏有一點利益衝突，”芝加哥大學(University of Chicago)行爲經濟學家理查德·塞勒(Richard Thaler)說。很多人辦了健身卡卻很少去這個事實，對國民腰圍不利，但對健身房老闆卻很有利。“如果他們成功地讓人們一週去三次健身房，而不是一個月三次，可能就沒法接納那麼多會員了。”

The more promising avenue may be employers. Ms. Royer hopes to later demonstrate not just that commitment contracts work to get employees to the gym, but also that they save employers enough through improved health to be worth paying for.
更靠譜的途徑可能在於僱主。羅耶隨後希望證明，承諾合約不僅可以頗有成效地促使僱員去健身房，還可以通過改善員工的健康，爲僱主省下足夠多的錢，從而讓僱主的投入物有所值。

For now, you can use a service like Stickk to set up your own commitment contract: Promise to go to the gym, and set aside money that will be given to charity if you don’t. For extra incentive, you can even use an anti-charity: If you don’t work out, your money will be given to a cause you hate. That’s more likely to keep you working out through beach season than simply paying up front for a gym membership.
目前，你可以用Stickk等服務制定自己的承諾合約：承諾去健身房，並留出一些錢，如果不去便捐給慈善機構。如果需要額外的激勵，你甚至可以利用自己不喜歡的機構：如果不鍛鍊，你的錢就會捐給你討厭的某項事業。和預先花錢辦健身房會員卡相比，這種做法更有可能讓你在整個去沙灘遊玩的季節堅持鍛鍊。