How Cherishing Mistakes, Being Clueless and Stress Fests Helped Birchbox's Success The founders of hugely successful beauty-subscription service Birchbox find strength in not having all the answers. For our series If I Knew Then, here are a few lessons and pieces of advice from Hayley Barna and Katia Beauchamp.

Birchbox founders and co-CEO's Hayley Barna and Katia Beauchamp are revolutionizing how you shop -- and help you discover your favorite quality beauty products by delivering samples right to your door, for just $10 a month.

The duo came up with the concept while attending Harvard business school. Inspired by the luxe beauty finds their friend (and first hire) Mollie Chen would bring home from her job as an editor at Condé Nast, Barna and Beauchamp wanted to bring this sample approach to the masses. Some 400,000 customers, the launch of Birchbox Man, a monthly-digital magazine and men's style guide, and expansions into France, Spain and the UK (thanks to the acquisition of Parisian service JolieBox) later, they've created an enduring brand and growing community. We caught up with Barna and Beauchamp to talk about finding balance and the courage to take the plunge into the unknown.

Q: Knowing what you know now, what would you have done differently when you were first starting up?
KB: Not knowing has had so much to do with our success. Of course Hayley and I had a big dream with Birchbox, but I believe a big reason we are successful is because we did not have the time to obsess about the long-term strategy. On a daily basis, the business was growing so quickly that Hayley and I needed to focus on keeping the customer experience strong and what needed to make that happen tomorrow and next week -- not in 12 months or five years.

HB: In terms of business approach, it's hard to say, because I really do cherish all of our mistakes. I look back on each of them as a learning experience that helped get us to where we are today. But one thing that I've gained perspective on lately, and I wish I had realized earlier is about balance and knowing that building a business is a marathon and not a sprint. In the early days the intensity and stress level of our work was through the roof -- very little sleep, not much personal time and every little thing felt hugely important. Perhaps that adrenaline level and total commitment are what a young business needs from its founders, but I'm pretty certain that there was a lot of energy that could have been put to better use.

Related: Harvard Students Reimagine the Cosmetics Business

Q: What do you think would have happened if you had that sense of balance then?
KB: I would have slowed down the growth of Birchbox and potentially shifted focus and resources to areas that make sense for a more mature company that we could study. The big problem with that is that there is no clear analog for Hayley and I to model our business after. We need to figure out what works for Birchbox, and not rely past precedent.

HB: If I had truly understood that being a balanced, calm and rested leader was more important than the extra hour of email from 1:00-2:00 AM, I would have been making better decisions and been a better role model for the team. If I had this perspective earlier, we could have avoided some burn out and created the more sustainable culture that we've achieved today.

Q: How did you learn this lesson?
HB: Over time as the business matured and grew, I learned to let go of the little things to trust my team and the momentum of the business. My first vacation post launch proved to me that even if I lost email service for several hours, not only would I be able to relax and have fun, but the business would not fall apart without me. I also remember a Sunday afternoon in the office with Katia when we talked about how much we loved building Birchbox, and if this was going to be our long-term career and a huge part of our waking lives, we better make sure we have fun doing it. When we take a step back, we are lucky to have the privilege of living through our toughest days as business leaders and it's important to remember that.

Related: Biggest Mistakes: Why Birchbox Says Timing Is Everything

Q: How do you think young entrepreneurs might benefit from this insight?
KB: There is a lot of positive in the unknown. You can see it as a positive and as something that frees you, rather than something that prevents you from taking action.

HB: When you're 110 percent committed to making your startup work it's tough to pull away from quantity of work to focus on quality. If young entrepreneurs are able to understand this earlier than I did, I think they could create a more sustainable approach to building their businesses, make better decisions on a day-to-day basis and store up their energy for the times it really matters to push hard.

Q: Besides inventing a time machine, how might they realize this wisdom sooner?
HB: In some ways, learning to create balance is something that must be learned over time. The amount of decisions you need to make on a day-to-day basis starts to feel normal, your confidence builds and the stress level recedes. But having a support network of friends and family outside of the business that can provide feedback and a safe haven from the workplace is important. Mentors can be a sounding board and shed light on unnecessary stress and achieving work-life balance. Also, it doesn't hurt to make rules. For example, choosing one day each weekend to totally unplug and then dedicating a set amount time for work is better than kind of working through the whole weekend. Little things like reminding yourself to get up from your desk and move around make a difference too.

Related: Birchbox and Changing the Way We Shop

Q: What are you glad you didn't know then that you know now?
HB: I'm really glad the business unfolded the way it did. If you had told me four years ago that we'd be running a business of this scale and a team of this size I would have been too intimidated to even start. But instead, little by little, Birchbox grew in the way it was meant to, and I was better prepared by my experiences to take on the next challenge as it came.

Q: What's your best advice for aspiring entrepreneurs?
KB: Go from aspiring to being as fast as you can. It is the best way to learn whether your idea has a customer and whether you love dedicating your days to see it come to fruition. Don't worry about realizing the full vision in the beginning but try to build a MVP [minimum-viable product] that allows you to test the key aspects of the model and the questions you have about it's potential.

HB: Don't just start any old business to start a business. Instead, make sure you truly love the concept and the team you're building it with. It's the best feeling in the world to make an idea a reality, but it's also going to be very hard work. It's the people you work with and the impact your have that make it worthwhile.

-This interview was edited for clarity and brevity.