Another good translation is "Never Forget Your Original Intention". The phrase is composed of the words Beginner's Mind (shoshin), %96Y%82%E9 (read wasuru) meaning "to lose (something)" and %83x%83J%82%E7%83Y (read bekarazu) meaning "must not; should not"
This is an ancient Japanese saying going back to at least the 13th century. In a slightly different form it appears as part of a Samurai Code which appears in English(ie "shoshin wo wasurubekarazaru koto") but does not appear at all in the Japanese sources that we could find .