We can change our mind’s constitution over time, while our basic physical constitution remains the same throughout life. Kathryn explains how what we experience through our senses (our food or home environment, for example) gradually affects the proportion of the three supreme qualities (maha gunas) that make up manas prakriti, our mental nature. These qualities are sattva (clarity and balance), rajas (movement), and tamas (inertia, dullness, and stagnation). Kathryn recommends yoga as a sattvic balance to rajas and tamas.