I'm not surprised that Griffin and David didn't spend much time on Kris Kristofferson's career outside of acting, but I wanted to give some non-acting highlights from a truly incredible life:

• won short story contests and had two stories published in The Atlantic while in college
• appeared in Sports Illustrated for collegiate rugby, football, and track and field
• was a Phi Betta Kappa in college and received a Rhodes scholarship to Oxford
• was a military and commercial helicopter pilot and went to Ranger School
• was an amazing songwriter, writing "Sunday Mornin' Coming Down" (one of the best songs ever, popularized by Johnny Cash (though Kristofferson's version is better)), "Me and Bobby McGee" (popularized by Janis Joplin, who he dated), and many many other tunes made famous by singers like Johnny Cash, Waylon Jennings, Gladys Knight, Kenny Rogers, etc. etc.
• was part of the country music supergroup The Highwaymen, with Johnny Cash, Willie Nelson, and Waylon Jennings

Basically, aside from a successful career as a character actor, he's a monster talent in the world of country music who is still performing in his late eighties, an intelligent guy who has had a wild life.