Part of me is a little jealous of those scientists – not because of the scientific breakthroughs (and destructive weapons) they created, but because of the opportunity they had to work and communicate with one another at all hours. Total immersion enabled greatness. Sometimes – especially late at night – when I have an idea I’m dying to share, I kind of wish Zillow Group had the kind of culture that permitted unfettered access, just like those scientists did in the 1940s. I have to hold back the momentary urge to call a colleague at midnight, because, while I have worked at places where that was acceptable, I don’t anymore. Once that urge passes, I’m grateful that a midnight brainstorm isn’t acceptable.

That’s because I used to work in a culture like that. In fact, I helped create it.

https://www.youtube.com/watch?v=W2eUrvj1Lok

I was 24 when I, along with a group of friends, started Hotwire. It was one of the most exciting times of my life. Hotwire had all the trappings of a 90s Bay Area startup, an almost-dorm room vibe complete with pyramids of beer cans in meeting rooms. Fueling our efforts was a motivating mission: to become one of the biggest travel websites around, when this was a new concept. With that came long hours and nightly group dinners – something pretty common for start-ups, then and now.

I didn’t mind the hours and neither did my then-girlfriend (now wife), who had just finished her master’s degree and was working in public health at Stanford University. We both understood the necessity of Manhattan Project-like focus at this stage in our careers. Dedication paid off – we sold Hotwire to Expedia in 2003 for around $650 million, but more importantly we created an innovative product and an enduring brand.

Following Hotwire, I joined the small team of Expedia veterans who were about to start Zillow. This time, things were different. Somewhere along the way, we’d all become real adults with commitments outside of work. My wife was pregnant when we started Zillow in 2006, and pretty much everyone else on the team was married with young kids. We knew 12-hour work days couldn’t be part of our culture and realized they didn’t have to be, because in place of frantic energy and flexible schedules, we had a new advantage: experience. This time around, we knew the kind of culture we wanted to build long-term, and our previous endeavors had given us the insight to know the creation of that culture would start from our very first employees.

This experience came to mind when I interviewed Dick Costolo for my podcast, Office Hours. The founder of Feedburner and former CEO of Twitter is currently starting his third company, a fitness software company, and we talked about how different the experience is to start your second or third company, versus your first. To sum up our conversation, culture is a tough thing to change, and it’s much easier to get your values to stick when they’re part of the foundation.

At his new venture, Dick is incredibly excited about the opportunity to establish a culture from the beginning, describing it as the most refreshing thing in the world. Dick believes there is no such thing as overinvesting in corporate culture – “not skateboards,” he says, “but values.”

I agree. While standing desks and organic snacks are appreciated by Zillow Group employees, these perks aren’t what inspire and motivate them to do their best work. It’s our mission of creating the largest, most trusted and vibrant home-related marketplace in the world, our core values of moving fast, thinking big and collaborating, and our recognition that each of us is a whole person and lives for more than just our jobs. We’ve invested in these cultural elements since the beginning, and they’ve paid off.

Click below to hear our talk.

Spencer Rascoff is CEO of Zillow Group.