However, on the day of the company’s initial public offering (IPO), Park decided to do something unusual: Donning a then unreleased blue Surge, the entrepreneur uploaded a trove of personal data that documented his heartbeat, sleeping schedule and biometrics leading up to the NYSE debut. The data provided a rare glimpse into the life (and health) of a CEO before the big day.

Below is an interview with Park taken a few days after the company went public on June 18.

Fortune: Walk me through how the idea to share your personal biometrics during the IPO process came about.

Park: From a product, business, and tech perspective, I think the whole idea of all these health and fitness wearables and sensors is that you can cover insights that weren’t possible or very practical before. So our products definitely enable the discovery of new insights and trends based on biometric data. And with the IPO I thought it was a pretty interesting opportunity to highlight the capability of what these devices are today and can become in the future.

At some point was there ever a realization or general notion about how weird the process would be?

No. I think it’s a couple things: One is these devices are really designed to fit really seamlessly into your lifestyle, so you generally end up forgetting a lot of the time that you have a Fitbit on until the moment you need to see the data, whether it’s on your device or in the app.

The second is that in general there’s always a lot of consumer awareness about security and privacy issues. For me, I’m always confident in the fact that my data is secure. Our privacy policy is also very clear as well, [and says] that we’re not going to sell data to third parties for either myself or any of our users. We’re only sharing data with very explicit, opt-in consent, and this was a case where I was consenting to have the data shared, so I was definitely comfortable with it all.

Walk me through what was going through your mind when you made the S1 announcement to your employees, and what caused such a high peak in your heart rate (the second highest for the day at 127 beats per minute).

I think probably for me it’s obviously the first company I’ve taken public, so at any time when you’re doing something new or novel you tend to get pretty excited, nervous, etc. I was definitely both of those things.

The other peak of 133 beats per minute took place at about 2:40 p.m. on the IPO day. I tried comparing it to the data provided from the rest of the day, and I couldn’t really figure it out. What was going on at that time that sent your heart rate soaring?

I’m trying to think. Pretty much all the events were over [at that time], and I think I was just really excited to try to find a hot dog. I think I was walking around pretty rapidly trying to find a hot dog stand. Not the most healthy, but New York has great hot dogs unlike San Francisco so that was clearly a focus.

What better way to celebrate taking a company public than with a New York hot dog?

Yea, a great way to cap off the day.

Can you put some context around why your sleep schedule varied so much. Was it strictly due to being up late working, stress, travel… or combination of all three?

I think, mainly, it’s very difficult to get consistent sleep because of all the timezone changes. We did a pretty comprehensive roadshow starting off in Europe, so Frankfurt, London. Then flying back to the U.S. and being in the mid-Atlantic (New Jersey, Baltimore, then New York, Boston, then New York again and back to San Francisco). Then [afterwards] to Los Angeles, Denver, Kansas City, Chicago and Minneapolis, so I think it was really all the changes in time zones everyday that made it very difficult to be consistent in sleep. I tried really hard to get a good nights sleep, but it was pretty challenging. A lot of times I would just try to use the weekend to see if I could catch up.

Throughout investor meetings your heart rate activity would usually peak at the beginning, and towards the end. However, I noticed, during one particular investor meeting your heart rate spiked several times. What happened?

A lot of times investors ask very tough questions, and it’s all very professional. A lot of times you welcome it because good, tough questions also force us to think more clearly about the business. I think this was a case of a meeting where we all felt that there were tough questions, but also maybe not delivered in the most professional way. That really resulted in, at least for me, my heart rate going up and being erratic throughout the meeting.

I’m sure if our CFO Bill [Zerella] was also wearing a Charge HR and published his data you’d probably see the same thing. It was definitely not a meeting we enjoyed and thought it was somewhat unprofessional.

Walk us through IPO day. As you rang the opening bell, your heart rate stayed at 86 beats per minute, which I thought was surprising.

I was surprised my heart rate wasn’t super high. I think it was mainly because I was trying to remain pretty calm. Because, you know, it’s never over until it’s actually over. I was trying to remain pretty calm throughout the whole process. In terms of particulars, or when I felt excited, it was not actually the ringing of the bell to open the market. It’s actually so choreographed that you get focussed on making sure you’re doing the right thing.

Whether it’s clapping, cause you have to clap for a certain period of time and then you gotta remember to press the button for ten-seconds and then let go. So you’re just focussed on making sure you execute all that stuff properly and you don’t really get to enjoy the event.

I did really enjoy the ringing of the physical bell and the gavel when the first trade of the Fitbit stock opened.

I would have expected to have been at a pretty elevated level during Jim Cramer’s (host of CNBC’s Mad Money) interview but I guess that didn’t show up either.

How do you stay so calm? Throughout this entire process your heart rate only peaked at 133 and that was for a hot dog. Outside of that, it just struck me that you’re a very calm person.

Throughout the process I would check my heart rate and try to make sure I was pretty calm. I don’t want to come off as very nervous. In general after 16 years of doing startups, you kind of get used to a high level of stress and it’s just something you become accustomed to.

Do you have any advice you can offer for controlling your stress in situations besides keeping an eye on your heart rate?

For me it’s just being very focused on the particular event. A lot of also has to do with preparation as well. The key thing is that before [our] interviews, we’d already done almost three weeks of roadshows and had almost 100 meetings with over 400 investors. That grilling really got us comfortable with the types of questions that could be asked about the company, the IPO process, the prospect for the company, etc.

A lot of being not nervous and stressed actually comes before it in terms or preparation.

The other thing too is that sleep is important. So every morning I would actually look at my sleep data to see how many hours of sleep I’d actually gotten and force—even though it was pretty challenging— myself to get a certain amount of sleep every night. And having that data was really helpful in trying to maintain that discipline.

I’m also generally a fit person, and I think keeping healthy is a pretty important part of managing the ups and downs of running a company.

Have you looked at your biometric data in relation to your [ongoing legal issues] with Jawbone so far, such as when you were first informed of the lawsuit and what the data looked like?

I don’t know if that’s something we can particularly comment on, but in general you’ve noticed I’m a fairly calm person and you can probably project that on to a lot of different situations.