Born on October 10, 1941 in Lelu, Kosrae State. President Nena attended Lelu Elementary School, Kosrae Junior High, and Intermediate School in Ponape where he graduated in 1961.

In 1961 to 1964, President Nena attended PICS High School and in 1964-1968 attended the College of Guam where he graduated with a BA degree in Political Science and a minor in English and Economics. In the summer of 1971, he was in a East-West Center grant and at the same time working for a graduate degree at the University of Hawaii. He graduated with a MA degree in Public Administration and Business Management at the University of Hawaii (Manoa) in 1972. He was the fourth Vice President of the Federated States of Micronesia for a second term in 1995. He became Acting President on November 8, 1996 when the FSM Congress members declared President Olter unable to discharge the powers and duties of his office after suffering from a cerebral vascular accident that occurred on July 16, 1996.

He became the Fourth President of the Federated States of Micronesia on May 8, 1997, 180 days after President Olter was unable to actively assume the duties of President, as provided in that declaration.

President Nena began his working career by teaching at PICS and was Political Affairs Officer for Ponape District from July 1969 to December 1969. In 1970, he became the Acting Distad Rep for Kosrae, and Deputy Distad Rep from 1970 to 1977. Nena became the first elected Governor for Kosrae State in 1979.

Nena was a member of the Micronesian Political Status and Transition Commission from 1979 to 1981, and in 1982 he accompanied President Nakayama to the South Pacific Forum. He was chairman of Lelu Municipal Government Constitutional Convention in 1986. He was the President of the Lelu PTA and Lelu Christian Endeavor. He was a member of the Kosrae State Constitutional Convention, serving as chairman of the Committee on Governmental Structures, and Operations. In the Fifth FSM Congress, Nena was a member of the Health, Education and Social Affairs (HESA), Judiciary and Governmental Operations (J&GO), and the External Affairs Committees. In the Sixth Congress, Nena served as chairman of HESA Committee, Resources and Development Committee (R&D) and External Affairs Committee.

His wife is the former Lerina Jack and they have ten children.