In an interview with Fast Company, former Apple employee Bob Messerschmidt, who helped design the heart rate sensors in the Apple Watch, gave some insight into what it was like working with Jony Ive and Apple's Industrial Design Group on the company's first wearable device.

After a 2010 acquisition, Messerschmidt joined the Apple Watch team, where he was in charge of designing some of the sensors for the device. In an anecdote relayed to Fast Company, during one meeting, Messerschmidt proposed putting health sensors in the Apple Watch band, an idea that was quickly shot down by the Industrial Design Group because of a desire for interchangeable bands.

One great example is [when] I went to a meeting and said I'm going to put sensors in the watch but I'm going to put them down here (he points to the underside of the Apple Watch band he's wearing) because I can get a more accurate reading on the bottom of the wrist than I can get on the top of the wrist. They (the Industrial Design group) said very quickly that "that's not the design trend; that's not the fashion trend. We want to have interchangeable bands so we don't want to have any sensors in the band."

Messerschmidt's next proposal was for sensors at the top of an Apple Watch worn tightly against the wrist, which was also nixed because "that's not how people wear watches." According to Messerschmidt, it was difficult working within the design constraints at Apple, but it pushed him to figure out "new engineering solutions" and ultimately made for a product with a superior user experience.

Engineers left in a vacuum might say "well, that's maybe not so important; we can get a better signal by doing it the other way so let's do it that way." So, left to their own devices, that would be the way the product would end up. So you have to have a really strong voice supporting the user. I think the idea of focusing on that is uniquely Apple

Messerschmidt goes on to explain other important lessons he learned from his time working at Apple and from Steve Jobs, including that user experience is "everything when it comes to consumer products," that "good enough is not good enough," and that it's important to say no "until it's just right."

Following three years at Apple and integral work on the heart rate sensor in the Apple Watch, Messerschmidt left the company to found Cor, a startup producing a device that draws blood, analyzes it, and provides near-instant health-related information.

Messerschmidt's full interview is worth checking out and can be read over at Fast Company.