One Source in Chinese / Japanese...

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.”

Taidō (The Way of the Body) is a style of Karate practiced in Japan and popular worldwide.

Taidō or 躰道 traces a lineage from Genseiryū (玄制流), which came from Shuri-te (首里手), one of the original martial arts schools of ancient Okinawa.

The first character 躰 is a variant of the original Chinese character 體. In modern Japan, they tend to use 体, a more simple character form. 体 is also the modern Simplified Chinese form of 體.
The 躰 character is correct for this 躰道 martial arts title. But it can be confusing with so many variants out there, not to mention other homophonic Japanese words that also romanize as Taidō or Taidou.

To have a bit more fun with this 躰 character, it has a 身 radical on the left, which sets it apart. The meaning doubles up on the “body” as 身 (shin) is a character that also means body in Japanese and Chinese. On the right is 本, which often means root, stem, origin, source, or fundamental (but can also mean “book” in some contexts). This has deviated from the original 體 which was 骨 (bone) + 豊 (vessel). Hence, the body was your “bone vessel” in ancient Asia.

The meaning of 躰, as well as 體 and 体, is usually translated as the body. When related to the physical body, it can also refer to the torso, trunk, build, physique, or the constitution of a person. As an extension of this, it can also refer to someone's health (good body = good health).
However, depending on the context, it can encompass other meanings such as form, style, system, experience, aspect, corpus, corporeal, substance, or essentials.

The second character, 道, is recognized and well-known as the “Way” and is the same “do” as in Karate-do or Aikido.

身土不二 (Shindofuni) is originally a Buddhist concept or proverb referring to the inseparability of body-mind and geographical circumstances.

This reads, “Body [and] earth [are] not two.”

Other translations or matching ideas include:
Body and land are one.
Body and earth can not be separated.
Body earth sensory curation.
You are what you eat.
Indivisibility of the body and the land (because the body is made from food and food is made from the land).

Going further, this speaks of our human bodies and the land from which we get our food being closely connected. This phrase is often used when talking about natural and organic vegetables coming directly from the farm to provide the healthiest foods in Japan.

Character notes: 身(shin) in this context does not just mean your physical body but a concept including both body and mind.
土 (do) refers to the soil, earth, clay, land, or in some cases, locality. It's not the proper name of Earth, the planet. However, it can refer to the land or realm we live in.

Japanese note: This has been used in Japan, on and off, since 1907 as a slogan for a governmental healthy eating campaign (usually pronounced as shindofuji instead of the original shindofuni in this context). It may have been hijacked from Buddhism for this propaganda purpose, but at least this is “healthy propaganda.”

Korean note: The phrase 身土不二 was in use by 1610 A.D. in Korea, where it can be found in an early medical journal.
In modern South Korea, it's written in Hangul as 신토불이. Korea used Chinese characters (same source as Japanese Kanji) as their only written standard form of the language until about a hundred years ago. Therefore, many Koreans will recognize this as a native phrase and concept.

See Also:  Strength and Love in Unity