Do you remember your first job? Maybe it was folding clothes in a retail store? Or perhaps it was delivering newspapers in your neighborhood, by bicycle? Was it scooping ice cream at a local sweet shop?

For most of us, first jobs bring to mind fond memories of summertime and, perhaps, a few lessons we’ve carried with us throughout our careers.

T Boone Pickens, Founder, Chairman and Chief Executive Officer at BP Capital and TBP Investments

Oil executive and financier Pickens got a paper route when he was 12 years old. It was the smallest route in his hometown, he wrote in his post My First Job: Not Getting Paid to Be Honest. Pickens had 28 houses to start, but eventually talked his boss into letting him add in routes that came open.

“Within five years my route grew from 28 papers to 156, and I had saved close to $200, which I hid in a hole under the floor in my closet. It was my first experience in the takeover field: expansion by acquisition,” he wrote.

But he learned another lesson, too, when he found a wallet on the sidewalk while completing his route.

“Inside it were the name and address of the owner. I delivered it to the man, and he gave me a dollar reward. It was a windfall,” Pickens wrote. “My mother, grandmother, and aunt were on the porch when I got home. They didn’t respond as I’d expected or hoped about the news of finding the wallet and getting the reward. Instead they sent me straight back to return the dollar to the man.”

Why? Pickens’s grandmother told him he was “not going to be paid to be honest,” he wrote.

Anne Toth, Founder and chief executive officer at Privacyworks LLC

Toth got her start in fast food — at the age of 14. She had to lie about her age to get the job. “You had to be 16 to legally apply for a job in Virginia. So… my application for Roy Rogers Restaurants said I was 16, and I looked and acted mature enough to make that plausible,” she wrote in her post My First Job: What I Learned as a Fast-Food Prodigy.

It was there that Toth learned five important lessons that she has carried with her, she wrote. Among them:

“Customers are often mean and demanding — just deal with it. Even fast food customers are paying customers, and I was taught at Roy's that they are always, mostly, right. I worked to make the customer happy even if I was sure the customer was a bone-headed Neanderthal idiot. Which I often thought. They were still the customer. I wasn't working the women's shoe department at Neiman Marcus, but I was going to try to act like it,” she wrote.

“Do a good job and you will be rewarded — with a harder job. By the end of my first week, having mastered the front line in record time, I was being trained to do the drive-thru window. It was at about this point that I started to realise that this was not considered a normal progression rate among the career fast-food people there. Working the drive-thru window was considered a promotion over the regular front line,” she wrote. “To do the drive-thru window you had to be able to listen to one order while filling the prior order and delivering/cashiering the order prior to that one. You had to be able to multitask... I was a fast-food prodigy, and everyone there knew it. Despite this recognition, I did not get a raise.”

That, of course, was a lesson in itself, she wrote. “Getting a promotion doesn't always mean getting more money.”

Brad Smith, President and Chief Executive Officer at Intuit

Smith’s first real job began when he joined Pepsi Bottling Group in 1996, just after graduating from university. “Pepsi had a career track for college graduates designed to teach the fundamentals of management,” he wrote in his post My First Job: A Lesson Learned in the Cola Wars. Upon completing a fast-paced 90 days foundational program, I was relocated to my first official assignment in Kalamazoo, Michigan, as a District Sales Manager.”

In Michigan, Smith was in charge of six route salesman and responsible for a sales territory with revenue targets and other responsibilities, including securing in-store and advertising campaigns. One management lesson, in particular, stood out, he wrote.

“One of my greatest lessons came from one of these leadership concepts that we referred to as ‘a one better mentality’,” Smith wrote. “In the mid-80’s, the Cola Wars were reaching epic proportions with advertising and endorsements that included Michael J Fox, Michael Jackson and Madonna championing the brand promise for the Next Generation. On the ground, my marching orders for my territory were clearly communicated — I was to find the person who had my job at Coke and apply a “one better mentality”. If my Coke counterpart had one display in a convenience store, I needed to have two. If they had 13 feet of shelf space in a supermarket aisle, then my goal was to have 14 feet.”

The concept was simple and the competition was thrilling, he wrote. But, a critical lesson emerged. “In 1991, I was inspecting our execution in a key account and nodding my head in approval as we had secured 16 feet in a major supermarket aisle as compared to Coke’s 12 feet” he recalled. “Then I looked to the left and saw 24 feet of bottled water. Bottled water? Who invited them to this fight?”

The lesson: “Being fixated on a single competitor can blind you to other disruptive entrants and substitute alternatives.”

What indelible lessons did your first job teach you? Join the conversation on BBC Capital’s Facebook page or message us on Twitter.