The beracha (blessing) known as Asher Yatzar is said after relieving oneself and makes us aware of the preciousness of being able to live our daily life in the fullness of our physical faculties and grateful for the normal functioning of our bodies, never to take it for granted.
Asher Yatzar can be used as a powerful segula (something that offers protection or serves as a remedy) for the refua shelema (complete recovery) of unwell people. We can dedicate our kavana (intention) while saying this beracha to people we know who need healing.
How can we do this? By reciting the prayer with intense concentration, thinking of its meaning, and remembering that HKBH is the true Healer. We ask Him to heal a specific person or persons by saying their full Hebrew name bat (daughter of) or ben (son of), and then their mother’s name (Ashkenazi tradition) or father’s name (Sefardi tradition). For example Devora bat Esther or David ben Rivka (Ashkenazi tradition); Devora bat Avraham or David ben Yitzchak (Sefardi tradition).
We can do the same to protect/guard our own health. In the words of the Seder Hayom: “If a person is complete in his attributes and he carefully utters his words, he will not become sick all of his days and will never need a doctor. Certainly, then one is to say the blessing with strong concentration and a complete mind to the healer of all flesh.”