This presents a huge growth opportunity, he said, noting that the company still has a "long, long way to go."
"When you look at companies like Amazon and Alibaba, the sheer size of what they've built is an extremely exciting opportunity," he said.
While Lazada shares a similar business model to Amazon, both selling their own inventory as well as allowing third-party merchants to sell their products on their websites, Bittner says launching an e-commerce business in Southeast Asia presents different challenges.
Read More Is the Philippines headed for a boom or a bust?
"When Amazon started in the U.S., it didn't have to think about how it would get the package to the customer – there was UPS for deliveries," he said.
Lazada has established its own fleet of couriers in each of its markets, which covers 30 percent of overall orders, he said. "In our market, we're not only dealing with logistics, the payment network is different. Our largest payment method is still cash on delivery," he said.
"One of the challenges is really guiding the customer through the shopping experience. For example, we send them a text message to say we've received the order. There's a lot of educating the customer through the whole shopping experience," he added.
Nevertheless, having the ability to make it more convenient for consumers in far-flung areas of Southeast Asia to purchase products that they would otherwise have to drive hours to buy, is highly rewarding, said Bittner.
Read More Five reasons to be positive on the Philippines
Another source of gratification is seeing the trust that investors have in us as a team, he said. Since its launch two years ago, Lazada has attracted investment from the likes of JPMorgan and most recently U.K. retail giant Tesco, which acquired a minority stake in the company in December.
"At the same time it's humbling because they clearly expect something for their money also," he added.
While Bittner's impressive resume includes Morgan Stanley, McKinsey & Company and e-commerce focused venture capital firm Rocket Internet, he says there are a few things that working at blue-chip companies can't prepare you for when it comes to entrepreneurship.
"One thing I wasn't taught is the people aspect of running a business, being able to manage big, big teams," he said. Lazada, which currently employs around 1,500 people across five countries, started with a core team of just 5.
"Also, what you don't expect is how much work it is...there's no weekend," he said.
"You can be prepared for a certain aspect of entrepreneurship, but in the end, what it really comes down to on a day-to-day basis is trial and error. Constantly improving and adjusting what you're trying to achieve, and having a flexible approach in the way you fulfill your vision," he added.