誠心 的英文怎麼說?

[1] (verb) have every intention of..[2] (adjective) genuine
  sincere
  heartfelt[3] (adverb) genuinely[4] find it in one's heart to do something[5] say it like you mean it

We have every intention of signing this contract. = 我們很有誠意想要簽這份合約

find it in one's heart 也很常用，例如:

I hope you'll find it in your heart to forgive me. = 我希望你能真心原諒我。

say it like you mean it = 真心誠意的說

heartfelt = 真摯/真心/誠心，是個很道地的英文，例如:

heartfelt emotions = 真摯的感情/情感
heartfelt apologies = 真摯的道歉/歉意
heartfelt thanks = 真摯的道謝/謝意