敞開心扉 is the most common way to express the idea of “Opening your heart” in Chinese.

This phrase is made up or two words:
敞开 = To open wide, to be unrestricted.
心扉 = Inner heart or soul.

If you want it brokend down further into individual characters:
敞 = Open to the view of all people, spacious, to open wide, or to disclose.
开 = Open, to start, or the beginning.
心 = Heart/Mind
扉 = Door, gate, opening, or the title page.

So maybe you can say, “To open wide the door of your heart and mind to all.”

Other variations of “open your heart” also exist such as 打開心扉, 敞開你的心扉, 打開你的心, and Simplified Chinese 敞开心扉, 打开心扉, 敞开你的心扉, or 打开你的心. These are also correct, but not as commonly used as 敞開心扉.

In mordern times, 開心 means to feel happy, to rejoice, or to have a great time, but directly translates as open heart.

In the Buddhist context, beyond opening the heart, it can mean to develop the mind, to initiate into truth, or awaken the mind.

開 = Open.
心 = Heart/Mind.

Not commonly used in Japanese where it might be read as open-mindeness.

虛心 is a Buddhist term that speaks of being open-minded and/or having a calm and humble mind or heart.

磊落 is a word that can mean big and stout, big-hearted, open and honest, or open-hearted in Chinese and Japanese.

開覺 is a Buddhist term meaning “open mind.”

The more full definition as used in Buddhism is, “To arouse, awaken; to allow the original Buddha-nature to open and enlighten the mind.”

虛己以聽 is a Chinese proverb that means to listen to the ideas of others with an open mind.

專心 makes a word that means “paying attention with your heart.”

It's often translated as “dedication,” as in “be absorbed in” or “concentrate one's efforts.” It's also used to mean “with the single mind,” “whole-heartedly,” “paying attention,” “undivided attention,” “concentration (-ed),” “engrossed,” “devotionally (listening/watching),” and/or “attentive.”

The first character means “for a particular person, occasion, or purpose,” “focused on one single thing,” “concentrated,” and sometimes, “special.”

The second character means “heart” or “mind” by itself.

My favorite translation, which comes from the Oxford Advanced Chinese/English Dictionary, is, “wholehearted devotion.”

If it seems like the meaning of this word is quite open, you are correct. The context in which the word is used matters a lot. It can mean different things depending on how you use it. This makes it kind of nice as you can decide what this means to you (within some limits). This is always positive in meaning, so even if a Chinese person reads it differently than you, it will still have a good meaning.

In Japanese, they tend to use a variation of the second character which has one less stroke. If you want your calligraphy written this Japanese form, please click on the Kanji shown to the right instead of the button above. Note: Japanese and Chinese people will recognize either form.

See Also:  Faith | Devotion

Beyond optimistic, 豁達 can also be defined as sanguine; magnanimous; open-minded; openhearted; broad-minded.

豁達 is appropriate if you are, or want to be, the kind of person who is not bothered by the little things or minor troubles of life. This signifies a person who always feels things will get better. This is great for the person who figuratively sees a window of opportunity opening even as a door closes.

While a valid word in Japanese, this is kind of antiquated, and not in common use in modern Japan.