けつい決意ketsui
1.

The act of clearly defining one's intended course of action or attitude, accompanied by a firm commitment to follow through with that decision.

2.

A profound mental state characterized by a strong intention to act on a significant matter, reflecting a determination that is unwavering.

3.

The process of making a definitive choice regarding an important issue, embodying the emotional resolve to see that choice executed.

Example:

彼女は私に自分の決意を知らせてくれた。