He was the prime minister of Norway from 28 August to 25 September 1963 in a coalition government consisting of the Conservative, Centre, Christian Democratic, and Liberal parties.

He raised the mountain cabin Skardøla in Sylene, about 50 metres from the Norway-Sweden border, which was used as an outpost by resistance fighters such as Odd Sørli, Johnny Pevik, and Nils Uhlin Hansen.

[1][2] Lyng was elected to the Norwegian Parliament from the Market towns of Sør-Trøndelag and Nord-Trøndelag counties in 1945, and was re-elected in 1949.

[1] His brief stint as Prime Minister came in August 1963 after the two representatives from the Socialist People's Party (SF) joined a slim 76-74 no confidence vote against the cabinet Gerhardsen following the Kings Bay Affair, a series of mining accidents at Ny-Ålesund.

Lyng quickly realised that between them, the non-socialist parties were only one seat short of a majority in the Storting, and that if they banded together, they would be able to form a government as long as the SF abstained.

[1] Although the cabinet Lyng only lasted a month, it proved that the non-socialist parties were capable of forming a government.