決心

The word "kesshin" describes more than just making a choice; it implies a strong mental commitment, resolve, or a firm determination to act. While "kettei" (決定) refers to a formal or objective decision (like a business decision or a scheduled date), "kesshin" is deeply personal and often involves overcoming hesitation or internal conflict.

It is frequently used in contexts where a significant life change or a difficult challenge is involved, such as starting a new career, ending a relationship, or committing to a strict habit. The emotional weight is higher than that of the simple verb "kimeru" (決める), suggesting that the person has "steeled their heart" to follow through with the action.

Commonly, it is used with the verb "suru" (to do/make) as in "kesshin suru" (to make up one's mind). When someone is still struggling to reach that point of resolve, the phrase "kesshin ga tsukanai" (cannot reach a decision/cannot make up one's mind) is used, highlighting the internal struggle before the final commitment is made.