[2][3] According to the Radiohead singer, Thom Yorke, he and the lead guitarist, Jonny Greenwood, wrote "Optimistic" in 1998 while traveling through a desert.

[1] The refrain, "Try the best you can / The best you can is good enough", was an assurance by Yorke's partner, Rachel Owen, when he was frustrated with Radiohead's recording progress.

[4] April Clare Welsh of NME interpreted the line, along with "flies are buzzing around my head / vultures circling the dead", as a possible comment on the pressures of fame.

[9] Sam Kemp from Far Out Magazine placed "Optimistic" in the last spot of a list ranking Kid A songs, saying that, although it is the most straightforward from it, it "just doesn't have that wonderful sense of unfamiliarity that defines so many of the tracks on the rest of the album.

[6] Marc Hogan of Vulture said that "Optimistic" "drew extra attention at the time for being a rare rock-oriented brooder on its Aphex Twin- and Autechre-aspiring album home.