At Ease in Chinese / Japanese...

四海為家 literally reads, “Four Seas Serve-As [my/one's] Home.”

Together, 四海 which literally means “four seas” is understood to mean “the whole world” or “the seven seas.” It's presumed to be an ancient word from back when only four seas were known - so it equates to the modern English term, “seven seas.”

This can be translated or understood in a few different ways:
To regard the four corners of the world all as home.
To feel at home anywhere.
To roam about unconstrained.
To consider the entire country, or the world, to be one's own.

踏實 means realistic or practical.

If you need a reminder to remain grounded in your life, this is a great way to do that. 踏實 also can have the meanings of “at ease,” “down to earth,” “to have peace of mind,” “free from anxiety,” steady, or steadfast.

默而识之学而不厌诲人不倦何有于我哉 is a quote from the Analects of Confucius that translates as:

To quietly recite and memorize the classics,
to love learning without tiring of it,
never be bored with teaching,
How could these be difficult for me?

This is a suggestion that for a true scholar, all of these things come with ease.

This was written over 2500 years ago. The composition is in ancient Chinese grammar and phrasing. A modern Chinese person would need a background in Chinese literature to understand this without the aid of a reference.

康 is a single character that means good health or vigor in Chinese, Japanese Kanji, and old Korean Hanja.

康 can also mean peaceful, at ease, or abundant in some contexts.

Please note that this is rarely seen alone in Japanese Kanji. In Japanese, it is used both for health-related compound words and to denote the kouhou through koushou eras of Japan.

In Korean, this can also be the family name “Kang” (caution: not the only family name romanized as Kang in Korean).

See Also:  Health | Vitality | Wellness

安心 can be defined as relief, peace of mind, feeling at ease, to be relieved, to set one's mind at rest, and easiness.

安心 is a nice word that encompasses great meanings within just two characters. Some of the other meanings include pacifying, settling the mind, and peace of mind. It's also the idea of feeling a sense of security, safety, and confidence in your state of well-being.

This can be used by everyone, but some consider it to be a Buddhist concept (You'll find it in your Zen dictionary).

Note: Can be romanized as Anshin or Anjin in Japanese.

樂 is a single-character form of happiness or bliss that holds the ideas of laughing and having a good time.

This can also be translated as happy, glad, enjoyable, fun, and sometimes, music.

This a really good character if your audience is Chinese.

This is not a word seen alone very often in Korean.

In Japanese, this character is written like the image shown to the right. If you order this from the Japanese master calligrapher, it will look like this instead of the character shown above.
Note: In Japanese, this has a meaning of comfort, ease, and enjoyment.

See Also:  Joyfulness

My Australian friends always say, “No worries, mate.” It's caught on with me, though I drop the “mate” part since it confuses my fellow Americans.

If you would like to express the idea of “no worries,” 放心 is the best and most natural way to say it in Chinese.

The characters you see to the left can be translated as “put your mind at rest” or “to be at ease.” You could literally translate “no worries,” but it doesn't “flow” like this simple Chinese version.

For your info, the first character means to release, to free, to let go, to relax, or to rest. The second character means your heart or your mind.

Note that in Japanese and Korean, this holds the similar meaning of “peace of mind” but can also mean absentmindedness or carelessness, depending on context.