Simplify the following text for a Grade 9 native English-speaking person.
Original: After he hosted a 1968 summer replacement for television 's The Smothers Brothers Comedy Hour variety show , Campbell hosted his own weekly variety show , The Glen Campbell Goodtime Hour , from January 1969 through June 1972 .
Simplified: Campbell guest-starred on The Smothers Brothers Comedy Hour , and later hosted a series of his own , The Glen Campbell Goodtime Hour .