Jason Segel was 25 in Tenacious D in The Pick of Destiny when he played the character 'Frat Boy #1 (uncredited)'.
That was over 18 years ago in 2006.
Today he is 44, and has starred in 33 movies in total, 23 of those since Tenacious D in The Pick of Destiny was released.
In Tenacious D in The Pick of Destiny, I think Jason Segel looks: