Strong Heart in Chinese / Japanese...

意志堅強 can mean either “strong-hearted,” “strong-willed” or “determination.”

The first two characters can be translated as “will,” “willpower,” “determination,” “volition,” “intention,” or “intent.” But, it should be noted that this first part possesses the element of “heart” in the lower portion of both characters (they also partially carry the meaning “with the whole heart”).

The last two characters mean “strong” or “staunch.”

Chinese word order and grammar are a bit different than English, so in this case, they are in reverse order of English but have the correct meaning in a natural form.

See Also:  Strong Willed | Discipline | Will-Power

気の強い means strong-willed or strong of heart in Japanese.

Here's the character breakdown of this Japanese title:
気 (ki) spirit; mind; heart; nature; motivation; intention; feelings; essence.
の (no) possessive particle.
強い (tsuyoi) strong; powerful; mighty; potent; resistant; resilient; durable.

Note: Because this selection contains some special Japanese Hiragana characters, it should be written by a Japanese calligrapher.

鉄心石腸 is a Japanese proverb that suggests you should have the inner-strength and will as hard and steadfast as iron.

It's the Japanese way of saying, “stay strong.” This is an especially uplifting thing to say to a person in distress or recovering from a disaster. It's kind of the survivor's creed.

If you literally translate this, it means “iron will, stone guts” or “iron heart, rock-hard bowels.”

有志者事竟成 is an old Chinese proverb that has been translated many different ways into English. As you read the translations below, keep in mind that in Chinese, heart=mind.

Nothing is impossible to a willing heart.
Nothing is impossible to a willing mind.
Nothing is difficult to a willing heart.
Where there is a will, there is a way.
Nothing in the world is impossible if you set your mind to doing it.
A willful man will have his way.
If you wish it, you will do it.
A determined heart can accomplish anything.
All things are possible with a strong mind.

不動心 is one of the five spirits of the warrior (budo) and is often used as a Japanese martial arts tenet.

Under that context, places such as the Budo Dojo define it this way: An unshakable mind and an immovable spirit is the state of fudoshin. It is courage and stability displayed both mentally and physically. Rather than indicating rigidity and inflexibility, fudoshin describes a condition that is not easily upset by internal thoughts or external forces. It is capable of receiving a strong attack while retaining composure and balance. It receives and yields lightly, grounds to the earth, and reflects aggression back to the source.

Other translations of this title include imperturbability, steadfastness, keeping a cool head in an emergency, or keeping one's calm (during a fight).

The first two Kanji alone mean immobility, firmness, fixed, steadfastness, motionless, and idle.

The last Kanji means heart, mind, soul, or essence.

Together, these three Kanji create a title defined as “immovable mind” within the context of Japanese martial arts. However, in Chinese, it would mean “motionless heart,” and in Korean Hanja, “wafting heart” or “floating heart.”

精神力量 is a title that speaks of one's soul or spirit and the capacity or strength that soul possesses.

The first two characters mean mind, heart, spirit, and/or soul.

The last two characters mean strength, capacity, or ability.

Note: Separately, these are two words in Japanese and can be pronounced, but this does not make a natural title in Japanese (best if your audience is Chinese).

思い切り can be translated as “with all one's strength,” “with all one's heart,” “to the limits of your heart,” or “to the end of your heart/emotions.”

The character breakdown:
思い (omoi) thought; mind; heart; feelings; emotion; sentiment; love; affection; desire; wish; hope; expectation; imagination; experience
切り (kiri) bounds; limits.

Note: Because this selection contains some special Japanese Hiragana characters, it should be written by a Japanese calligrapher.