Lyman was a first-chair bass player with a number of amateur and semi-professional symphonic and chamber orchestras.

Lyman narrated the highly rated Vietnam: A Television History, a 13-part documentary series about the war that was produced by WGBH in Boston in 1983 and broadcast nationally by PBS.

He has also appeared on the TV shows Commander in Chief, in which he portrayed the President of the United States (whose death in the story elevates Geena Davis' Mackenzie Allen to the office), and also appeared in TV shows Threat Matrix, The West Wing, and Law & Order.

He narrated a series of commercials for the Mexican beer Dos Equis, revolving around their character of "The Most Interesting Man in the World", portrayed onscreen by actor Jonathan Goldsmith.

Lyman continued to be active and appear on stage at the Huntington Theatre Company in Boston, Massachusetts in Romeo and Juliet (2019), Guess Who's Coming to Dinner (2014), All My Sons (2010) and Dead End (2000).