Literally: heart – mechanism – one – turn
Alternately: A complete change (for the better) in one’s emotional state in response to something. A fresh outlook on life. Turning over a new leaf.
Notes: There are many ways to get this one wrong: for shinki, 新規, 新気, 心気, and 心器 are all possible renderings that people may try. All are incorrect. This does offer an interesting insight, though, into how people’s minds interact with kanji. It seems that the phonetic and semantic information is easier to retrieve than the associated visual symbol, leading people to use kanji with the same pronunciation that produce related, or at least plausible, meanings.