“Notifications was supposed to be telling me something that I needed to know in the moment,” said Cook. “And so I began to start slashing the number of notifications I was getting. This winds up helping you a lot.”

Cook said Apple developed the feature to help people become aware of how they using their iPhones.

“I think it has become clear to all of us that some of us are spending too much time on our devices,” Cook said. “And so what we have tried to do is then think through pretty deeply well, how could we help with that? Because honestly, we have never wanted people to overuse our products. We are not about usage. We want people to … to be empowered from them and to be able to do things they couldn’t do otherwise.

“If you are spending all the time on your phone, you are spending too much time,” Cook said.

In January, two major Apple shareholders — Jana Partners and the CalSTRS (California State Teachers’ Retirement System) — sent a letter to the tech giant urging it to address worries that the iPhone is addictive and that overuse has the potential to cause “long-term consequences.”

“Apple can play a defining role in signaling to the industry that paying special attention to the health and development of the next generation is both good business and the right thing to do,” the letterread. “There is a developing consensus around the world including Silicon Valley that the potential long-term consequences of new technologies need to be factored in at the outset, and no company can outsource that responsibility.”

Cook said the roll out of the iPhone activity monitoring feature in was not in response to any particular objection. He said Apple has long been invested in giving parents the ability to monitor the usage of their kids’ phones.

“We have been working on starting with parental controls since the beginning, right?” says Cook. “And so we have always taken a level of responsibility here. Parents have had the ability for years to select which apps go on their kids phones, which apps don’t … and also to monitor or to not allow explicit songs, to not allow anything other than G-rated movies and so forth, and so there has been a fair amount of control there.”

The challenge with monitoring the usage of iPhones, said Cook, is that every individual has different patterns and habits. “This is not an area where, like exercise, where you can say 30 minutes a day is kinda good for almost everybody,” says Cook.

All iPhone users will have access to the information about their own usage. “We want everybody to have this information and then you can do what you want to with it. You might say, ‘I don’t want to know any of this,’ says Cook. “You might do like I have done … is you started saying, ‘Well, I can make this change and this change and this change.”

See also:

Like this story? Subscribe to CNBC Make It on YouTube!