Washington (CNN) -- After four and a half years at the helm of the National Counterterrorism Center, Michael E. Leiter is ready for a change of pace.
"This is a job where you have to be running 100 percent of the time, full speed, constantly," he says.
Now he will have an opportunity to slow down. Leiter steps down next week.
The center was created after the September 11 attacks to integrate and analyze intelligence from across government and around the world.
"We are awash in threats all the time," Leiter says, "handling between 6,000 and 10,000 pieces of terror-related intelligence every day."
Leiter has watched the terror threat become more diverse.
His biggest worry at the moment is a strengthening al Qaeda in the Arabian Peninsula, which is exploiting the unrest in Yemen to expand its safe haven. Although he will not discuss operational planning, Leiter acknowledges the situation also presents opportunity for the United States.
"We look at this as an excellent time to take the fight to the enemy," he told CNN in an exclusive interview.
That includes striking al Qaeda central, which Leiter believes is vulnerable after the death of Osama bin Laden.
The raid on bin Laden's compound in Pakistan counts as one of the high points in his tenure. He says relief was the primary emotion in the White House situation room when bin Laden was killed. There was no rejoicing, according to Leiter.
He called a family member of a September 11 victim to share the news. "We had been working on this for so long and so hard and to have some success, that was incredibly gratifying," Leiter says.
According to Leiter, the low point in his tenure was the attempt to bring down an airliner over Detroit on Christmas Day 2009. Umar Farouk Abdulmutallab allegedly tried to ignite a bomb concealed in his underwear.
The NCTC was harshly criticized for failing to pick up on the plot beforehand. Leiter says some of that criticism was justified and served as a wake-up call.
"The organization at that point, and I at that point, had an opportunity to make a choice. Did we kind of curl up and die? Did we not accept legitimate criticism? Or did we take the legitimate criticism and improve the center? I think we chose the latter, and I am quite proud of that," Leiter says.
As the investigation of the underwear bomber unfolded, Leiter went on vacation with his young son. White House Counterterrorism Adviser John Brennan said he had approved the decision, but Leiter was nonetheless pelted with criticism.
He now regrets that he didn't cancel the vacation and stay in Washington.
"I have regrets because it left an image of NCTC, and it left an image of the counterterrorism community, as not being 100 percent focused on these issues all the time," Leiter said. "And I was extremely regretful, and continue to be, that my choices ended up reflecting badly on the organization and the administration. I'm very sorry about that."
Leiter leaves his job Friday.
He says he will likely work in the private sector, speak and educate others on terrorism prevention.
President Barack Obama intends to nominate Matthew Olsen as the next director, the White House announced Friday. Olsen currently serves as general counsel at the National Security Agency.