Metro Manila (CNN Philippines) — Las Piñas Rep. Mark Villar believes destiny has led to his appointment as the next public works secretary, a job he says may be the biggest challenge in his life.

Incoming president Rodrigo Duterte named Villar, 38, among his first appointees to the new Cabinet.

Read: Mark Villar accepts Duterte's offer to be DPWH secretary

"This is probably the biggest challenge of my life," Villar said in an interview with CNN Philippines on Wednesday (May 25).

"This all came as a big surprise to me,” he said. “When I started my political career, I never imagined I would end up in this post, but I'm here and this is where destiny has taken me. I'm going to make the best of it."

Villar, who won his third term as Las Piñas representative in the May 9 polls, earlier said he hesitated accepting the appointment but eventually agreed after consulting his family and constituents. He said he will resign from congress when his Cabinet appointment is formalized to make way for a special election to choose his replacement.

"It's a great honor for me to have been chosen by the mayor and presumptive president," Villar said. "It's not something I take very lightly. At this point, the idea that I can really make a lot of changes, it's very appealing to me. Hindi na ako aatras [I won't back down]."

How will he handle a possible conflict of interest between his position as secretary of the Department of Public Works and Highways and his family’s vast real estate business?

Villar, a son of former Sen. Manny Villar and Sen. Cynthia Villar, vowed his post won’t benefit his family’s businesses.

Related: Duterte defends cabinet appointees: ‘They are not corrupt’

"I now say this categorically: there will be no business of my family that will benefit from my position in the DPWH. That is definite. I would not do it and I would not allow it," he said.

Duterte told reporters recently that he has asked Villar to submit a map showing the Villar group’s real estate projects and directed the incoming public works secretary not to build any roads or alleys to those developments.

Keenly conscious of his family’s business interests, Villar promised he would be “more careful” and not take advantage of his position as DPWH secretary in order not to sully the family name.

“That is not why I entered this," he said. "I entered this because it's a challenge for me and I can say with absolute certainty that these fears are unfounded.”

Villar said it is logical for a new president to fill up a certain Cabinet position with someone who has experience related to the department’s line of work.

In his case, he said he has “extensive experience in master planning” as well as politics and business. Also, as a young man, he said he will introduce “fresh ideas from my generation and bring in some idealism and new blood into the DPWH.”

He said he has spoken with DPWH Secretary Rogelio Singson, whom he holds in high regard, and build on the reforms of the outgoing public works chief in the corruption-tainted department. Villar said he wants to “create a new perception” of the agency under his leadership.

Despite the weight on his shoulders of his new job, Villar appears eased by the thought that "there's never going to be progress without pressure."