Thayer was born right here in Arizona in 1961, the son of a mechanic and a school teacher. Thayer's father worked at the Yuma Proving Grounds, and his mother was his 7th-grade Civics teacher. Growing up in Wellton, about 30 miles east of Yuma, Thayer lettered in football, tennis, and track in high school, and was elected president of the Science Club. He graduated from Antelope Union High School in 1979.

After high school, Thayer worked for Yuma News Inc. and then for the Wellton Mohawk Irrigation District until beginning his mission for the Church of Jesus Christ of Latter Day Saints in 1981. After serving his church in Louisiana, Alabama, and Mississippi, Thayer joined the U.S. Army in 1983. Between 1983 and 1986, Thayer served as a Nuclear Biological and Chemical (NBC) Specialist; a paratrooper in the 82nd Airborne Division stationed at Ft. Bragg, NC; and attended the Jungle Operation Training Center in Panama.

Between 1986 and 1992, he served in the active Army Reserves as the Assistant NBC Noncommissioned Officer in charge of NBC training.

Thayer attended Mesa Community College from 1987-1989, and was elected Student Body President and Chairman of the College Republicans Club. In 1993, Thayer earned a Bachelor of Science Degree in Political Science from Arizona State University
Thayer has been a Precinct Committeeman in District 30 (now LD22) in Gilbert/Mesa since 1987. He also served as Vice-Chairman and as State Committeeman.

In 1997, the Thayer was elected Chairman of District 30(now LD22). Under his leadership, the district saw an increase in Precinct Committeemen of over 100%, and substantial growth in the district treasury.

Thayer and his wife Carla, have been married for twenty years, and have 5 children, ages 17-25. Their 3 sons served missions one in New Jersey and two in Spain.