Definition of Konjoe: 根性

Optional soundtrack: The Rolling Stone's Street Fighting Man
根性 【こんじょう】 (n,vs) will-power; guts; temper; nature; spirit; (P) (From WWWJDIC)
I found this kanji when first came to Tokyo and was absorbing Japanese business books. After exhausted the supply of books I found in the US, I moved on to Tokyo bookshops. All of these books tended to follow a form, where they contained tips and keywords to describe characteristics and praiseworthy traits. 根性 was one of the keywords that stuck with me.
Recently, 根性 has been negatively associated with militarism but is also used in association with sports. Originally derived from the Buddhist tenant that "根性はその人間が持って生まれた性質" or that "Spirit is an innate feature of human nature." (This is my own translation, so I'd appreciate suggestions to improve it).
根性 is also used in numerous idioms, such as "かむ根性が無いなら、歯を見せるな" or "If you cannot bite, do not show your teeth." It's not always used in a positive fashion though, as the absence or perversion of this trait can be quite negative. For example, 泥棒根性 means a "thieving nature."
To help with kanji I carry a notebook (now in volume 4) and I used to write some of my favorite ones on the top of my hand under my watch (alla S.P.E.C.T.R.E). This was the kanji that carried to my first sleepless day of work a lifetime ago.