Health is one of the most important benefits of yantras. The following excerpt is from an article written on Uplift.
The Tantric texts describe yantras as a means to actualize greater health and well-being. Science confirms that visualization is a potent form of concentration due to the dominance of the visual cortex. When a visual pattern is introduced and reinforced it enables us to let go of our preoccupations with thoughts, in turn releasing stress and bringing the whole mind-body system back to balance.
Mavis Gewant, an American sacred artist, mother, educator and doula, learned the ancient techniques of Yantra and deity painting from Tantric Master Harish Johari after meeting him in Amsterdam in 1979. She never planned to paint Yantras, but Johari recognized her gifts and inspired her to mentor with him and share her knowledge worldwide.
I believe that Yantras are a personal prescription for healing. Whether with a deity or a planet, it is an energetic entity you are working with to heal and create a connection in a very deep way. Personally I have experienced working with specific Goddesses and I have taken on those qualities to create change in my life. For example, The Goddess Kali, is one to invoke when you have a fear of death. As the Goddess of Transformation, she will get rid of things that are no longer necessary in your life, and I have experienced that firsthand.
Yantras give a pattern to energy. Since all cultures have these kinds of shapes, they resonate in our DNA when we see them. By creating a Yantra, one sits for hours absorbed in the energy of the particular deity they are working with. When one chants the corresponding Mantra, both hemispheres of the brain are activated, eventually creating a state of one pointedness, healing and transformation.