Many executives yearn to run a company someday. Few succeed.

Doug Conant and Fred Hassan know how to up the odds. The former chief executives have helped numerous protégés make it to CEO.

Five lieutenants from Mr. Conant's decade atop Campbell Soup Co. landed the No. 1 job at a public company. They include Sean Connolly at Hillshire Brands Co. and Chris Delaney at Goodman Fielder Ltd.

The same dream job came true for eight associates of Mr. Hassan, a prior chief of Pharmacia Corp. and Schering-Plough Corp. Among them: Stephen P. MacMillan at Stryker Corp. and Hugh Grant at Monsanto Co. (A ninth, Brent Saunders, will take the helm of Forest Laboratories Inc. on Oct. 1.)

There is no secret recipe for landing the corner office. But there are plenty of ways that a strong CEO candidate can veer off track, leadership specialists say.

Some fall short after rationalizing missteps by 'looking at the world through rose-colored glasses,' Mr. Conant says. Other unsuccessful aspirants typically 'lose their humility,' adds Mr. Hassan, who wrote a leadership book - as did Mr. Conant (though with a co-author).

'A lot of time promising people fail to become a CEO because they have huge blind spots and lack corrective feedback from an internal mentor,' says Thomas J. Saporito, head of RHR International LLP, a management consultancy.

Some corporate boards mainly look at an executive's track record, industry knowledge and management experience.

However, other corporate boards keen to change commanders 'are paying way more attention to the softer skills like leadershipability and cultural fit,' reports Jeffrey Cohn, a partner in the leadership consulting practice for recruiters Heidrick & Struggles International Inc.

Here are four leadership lessons fostered by Messrs. Conant and Hassan -- along with insights four protégés gleaned from their informal grooming:

'Sometimes you have to be deliberate, and sometimes you have to be more active,' Mr. Conant observes. But figuring that out isn't always obvious.

Mr. Connolly took charge of Campbell's U.S. soup business in 2004, two years after his arrival. He knew nothing about the flagship product line, which was growing slowly. The young general manager proposed taking time to learn the business.

Mr. Conant disagreed. 'We need to get it moving,' the CEO urged Mr. Connolly during a face-to-face meeting. 'Take no prisoners.'

So Mr. Connolly acted fast. His unit's results improved in a year. 'For the first time in modern history, we restored our flagship condensed soup to growth,' he says.

Growth revived partly through innovation, such as a line of gourmet bisques that required a new technology. He later oversaw North America, Campbell's biggest division.

Hillshire appointed Mr. Connolly CEO in June 2012, after the food company, previously called Sara Lee Corp., spun off its tea and coffee business.

Mr. Hassan brought Mr. MacMillan to Pharmacia in 2000 to oversee consumer products and four smaller divisions. He says he soon alerted fellow directors that the executive 'could be a potential CEO.'

Ahead of board presentations, he coached Mr. MacMillan to keep things simple, leave time for frank discussion and 'show your humility,' Mr. Hassan remembers. 'Really value what (directors) say,' he told his protégé. 'It can't be fake.'

Pharmacia board member William U. Parfet was so impressed that in 2003, he recruited Mr. MacMillan to be president of Stryker Corp., where Mr. Parfet also was a director. Promoted to CEO of the medical-device maker at age 41 in January 2005, Mr. MacMillan won analysts' accolades for its steady performance as the orthopedics market stalled.

Yet Stryker forced out Mr. MacMillan early last year, partly because some directors were bothered by his relationship with an ex-flight attendant for its corporate jets while his wife pursued a divorce, people familiar with the situation have said. In hindsight, Mr. MacMillan realizes he joined Stryker when he had just begun to grasp the nuances of board management from Mr. Hassan.

'Managing a board was not my strength at Stryker,' Mr. MacMillan concedes. 'It hurt me.' He now leads sBioMed LLC, a private manufacturer of infection-control products.

The next time he becomes a public-company CEO, Mr. MacMillan vows to be 'more measured, mature and open with my board - while more patient in changing out board membership.'

As second in command of Monsanto, which Pharmacia acquired in 2000, Mr. Grant watched Mr. Hassan extensively use multifunctional teams. 'He'd bring together multiple functions, all with equal say in pushing an idea forward,' he recalls. 'Fred was always absolutely engaged.'

Mr. Hassan believes the approach hastened Monsanto's integration. Pharmacia subsequently spun off the world's biggest seed producer by revenue. Mr. Grant advanced to Monsanto CEO in 2003.

The Pharmacia experience gave Mr. Grant a role model for being an effective CEO. He says Mr. Hassan was 'very, very open to hear a wide range of opinions,' and multi-functional teams 'improved the quality of decisions' made by Mr. Grant and Monsanto colleagues following its spinoff.

Since becoming CEO, 'there's hardly decision made where I am not involved with a team that's totally multifunctional,' Mr. Grant says. 'You don't act engaged. You are [engaged].' He participates in such team meetings at least once a week.

Mr. Delaney, hired by Mr. Conant in 2004, stumbled while president of Campbell's emerging markets division three years later. A soup broth introduced in parts of mainland China flopped after six months. 'It was a very expensive starter,' he recollects. 'I had to stand up to Doug and tell him I disappointed him.'

His team developed a different version closer to finished soup, 'but that version still hasn't cracked the code,' Mr. Delaney says.

By takingresponsibility for the setback, Mr. Delaney 'demonstrated managerial courage,' Mr. Conant says. He subsequently elevated his lieutenant to run Asia-Pacific for Campbell.

Goodman Fielder, Australia's biggest public food company, picked American-born Mr. Delaney as CEO in 2011. He says he continues to imitate other aspects of Mr. Conant's leadership.