At age 14, Hastings became a school teacher in Clinton County, Pennsylvania, a job he held for four years.

Involved in local government and civic institutions, Hastings served on the Bellefonte school board, as a town Burgess, a trustee of Bellefonte's Methodist Episcopal Church, and a trustee of Pennsylvania State College and Dickinson College.

Daniel Hastings was initiated into Bellefonte Lodge # 268 of Free and Accepted Masons in September 1874.

In 1886, he was a delegate to the state Republican convention, and gave the nominating speech for Beaver, who ran successfully for governor.

Hastings was a delegate to the 1888 Republican National Convention, and gave the nominating speech for John Sherman.

In July 1877 Hastings joined the Pennsylvania State Militia as paymaster of the 5th Regiment with the rank of Captain.

In his role as adjutant general, Hastings led relief efforts following the 1889 Johnstown Flood, for which he gained statewide attention and praise.

[6] In 1897, the State Capitol Building in Harrisburg was destroyed in a fire, and the Hastings administration started efforts to erect a replacement, which was completed in 1906.

Hastings directed the state's response during the Spanish–American War, working with the state legislature to raise troops, supplies and equipment and transport them to mobilization sites, and then taking steps to return soldiers to Pennsylvania and demobilize them at the end of the war.