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The Co-Founder Behind Slack Shares What He Did 140 Times Last Year Alone -- and How It Helped Prevent Burnout Slack's co-founder and CTO Cal Henderson explains how to make sure you're not overwhelmed so you can accomplish your biggest goals.

By Nina Zipkin

Courtesy of Cal Henderson

Editor's Note: Entrepreneur's "20 Questions" series features both established and up-and-coming entrepreneurs and asks them a number of questions about what makes them tick, their everyday success strategies and advice for aspiring founders.

If Cal Henderson's experience is any guide, you shouldn't be afraid to change things up if an opportunity comes your way.

Henderson is the co-founder and CTO at the popular messaging platform Slack. But the Slack today wasn't what Henderson and his co-founders set out to make.

When Henderson, a computer programmer by trade, first started working with CEO Stewart Butterfield, it was to develop video games.

Their first attempt turned into the photo sharing website Flickr. They then tried again to break into the gaming space, but it didn't work out. Despite it going bust, the team continued using the messaging platform they had built on top of it.

"It was all very crappy and cobbled together, but it was a good way of working," Henderson told Entrepreneur. "We wanted to try to turn it into a product for other people and that that turned into Slack."

Today, Slack has expanded to eight offices all over the world and has more than 1,000 employees. The company has 8 million daily active users, and its customer base includes 65 percent of Fortune 100 companies. As of the fall of 2017, the business was bringing in $200 million in annual recurring revenue.

We caught up with Henderson to ask him 20 Questions and find out what makes him tick.

1. How do you start your day?
I check my Slack notifications to see if anything super important happened overnight night [and decide how to address it]. Something that's really nice working in enterprise software compared to the gaming space is people play games in the evening and on the weekends, but people use workplace software during the working day. So if anything is going to happen, it happens when you're in the office.

2. How do you end your day?
I listen to books at the end of the day to help disconnect from work -- so I'm not going to sleep thinking about work.

3. What's a book that changed your mind and why?
It's a sci-fi book called The Golden Age by John Wright. It's set a few thousand years in the future. It's a utopia compared to now, but everybody is still full of problems. [It helped me realized that while] technology can make our lives better, humans are still going to be human [no matter what.] We're kind of stuck with being who we are.

4. What's a book you always recommend and why?
The Diamond Age by Neal Stephenson. It's a slightly steampunk vision of the future, but it's a vision of the future in which there's still a lot of wealth disparity and corporations run the world. It is a an approachable future-prediction-type of science fiction.

5. What's a strategy to keep focused?
I'm always looking at my calendar for what I'm doing next and understand how I'm allocating my time. Of the three biggest things I want to accomplish that week, how have I allocated time to those people [and goals]?

6. When you were a kid what did you want to be when you grew up?
From the time I was 5 I wanted to be a programmer. My cousin who's a couple of years older than me got a home computer. I saw it, and it had programming built in. I thought, yes, I want to do this.

7. What did you learn from the worst boss you ever had?
I've never had a truly terrible boss. People are just trying to run a business, live their lives and scrape by from day to day. And the concerns of their employees are not in the top 50 things they need to stress about that week. It's super tough running a business.

8. Who has influenced you most when it comes to how you approach your work?
Since my son was born, it has changed how I prioritize work. When I was a younger, work was by far the most important thing that I did, and I built my life around my work.

9. What's a trip that changed you?
When I was working remotely for a Flickr, I went to visit them in Canada for three weeks and never went home.

10. What inspires you?
People creating independent stuff on the internet -- that people can create stuff and put it in front of an audience of hundreds or thousands of people. That's what got me into the web.

11. What was your first business idea and what did you do with it?
Making video games, [which] is really interesting, super difficult and most people fail at it. We have a channel in our Slack called "games we won't finish.'

12. What was an early job that taught you something important or useful?
I worked in a pub in the UK serving food for a few years. I learned that it's not only the product you are delivering; the customer service side makes a huge difference. It's always the same food served week to week, but how you treat angry customers, or just your interaction with anyone, can make a huge difference. Also, the attention to detail around the experience is an important and powerful piece of a product.

13. What's the best advice you ever took?
I had a fairly steady job in my hometown working in a small web agency. I had this offer to go work with a small team in London doing an experimental thing that almost certainly wouldn't work out. The advice I got was go do something exciting and different and try it out. It was a hot mess in the end, but it is part of the path the led me to where I am now.

14. What's the worst piece of advice you ever got?
People advised me to drop out of university. I was working full time in London and going to university two hours away at the same time. It wasn't a super useful experience when I went to university, but if I hadn't have completed it, I wouldn't have been able get a visa or move to Canada and eventually move to the states.

15. What's a productivity tip you swear by?
I rank the three most important things I want to achieve that day and then look back at that list as often as I can. It's a simple productivity hack, but it keeps me focused on what I want to do.

16. Is there an app or tool you use in a surprising way to get things done or stay on track?
The planning and execution of my job is very oriented around Slack, which means prioritizing which channels I need to follow and which are just informational and in the background.

17. What does work-life balance mean to you?
Since I had kids, my life has become a lot more balanced. I want to be able spend all the time I can with my son, and work is priority number two. On a more like philosophical basis, work-life balance means there is something that you think about in your spare moments besides work. It is super important to have other interests and things to fill up your spare time, or you probably will go insane.

18. How do you prevent burnout?
Listening to audiobooks. I listened to 140 books last year. Because an audiobook requires proper mental focus, it forces me to stop thinking about whatever I was thinking about before.

19. When you're faced with a creativity block, what's your strategy to get innovating?
I seek out projects that people I know in my network have worked on and look at interesting new work people are doing.

20. What are you learning now?
Our company has grown so much over the last few years. So, it's a constant learning experience. Every day when I go to work, it's the biggest company and organization I've ever run. Having to re-learn how to do everything on a rolling six months to year basis is both terrifying and exciting. It's a chance to rethink how we do everything.

Nina Zipkin

Entrepreneur Staff

Staff Writer. Covers leadership, media, technology and culture.

Nina Zipkin is a staff writer at She frequently covers leadership, media, tech, startups, culture and workplace trends.

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