The Greatest Hits - Why Try Harder is a 2006 compilation album by Fatboy Slim, released in June 2006. In addition to previously released material, the album includes two new tracks: "Champion Sound" and "That Old Pair of Jeans". A collection of music videos titled The Greatest Hits - Why Make Videos was also released in 2006.
To save space on the audio disc, the songs are shorter radio edits with the exception of the final track. The profanity in "Wonderful Night" remains intact in the United Kingdom edition, but was removed for the United States. "Champion Sound" is also significantly different on the U.S. edition, as it contain verses that are absent from the UK release. The album sold 20,014 copies in Japan in its first week.
For the U.S. release, the front cover was altered to that of Christopher Walkenfrom the "Weapon of Choice" music video. The title of the compilation comes from the slogan on the T-shirt of the obese man who adorns the non-U.S. covers of both this album and You've Come a Long Way, Baby, "I'M #1 SO WHY TRY HARDER".