The only consistency is change, a topic I've written a few times before.
Change is so challenging, that every religion or spiritual tradition acknowledges this, and tries to give us guidance... comfort. Because it's our fear of changing, or grasping to the past, that causes so much suffering.
When teaching and practicing yoga I encourage students to let their breath adapt naturally and fluidly like water to all the circumstances that arise. Some breaths will be longer, some will be more shallow.
This is like life; our mind, body and emotions are reflected in the breath. Learning to be with, and read the messages contained within your breath is the sweetest and simplest way to practice.