For a short time he was the drummer for the band Cadillac, and later became a member of La Década Prodigiosa.
He also wrote songs for other artists, including "Tractor amarillo" which was a hit for the group Zapato Veloz in 1993; and "La Puerta del Colegio" (1991) and "Mi Amada" (1993), hits for the Mexican group Magneto (along with Alberto Estébanez).
He released several solo singles in the 1990s, and "Hasta el final del mundo", a duet with Mónica Naranjo.
[2] In 2001, Herzog joined the team of reality TV singing competition Operación Triunfo, which served to select the Spanish entrant for the 2002 Eurovision Song Contest.
Herzog was the post-academy director, responsible for ongoing coaching of eliminated contestants, some of whom would provide backing vocals for the ultimate winner of the show.