Before each of my classes, I put a lot of thought and preparation into what I plan to teach, and seldom do I teach what I've planned. It all depends on who shows up. It's a great way to practice pratyahara, non-attachment. It took me several years to learn to go with the flow, in other words, teach to who shows up and what their needs are. Another bonus is that I practice the sequence anyway, so I get a good workout. I selected the literal meaning from the link above. I highly recommend reading the full article to see how pratyhara applies in your life.
Pratyahara means literally "control of ahara," or "gaining mastery over external influences." "Ahara means "food," or "anything we take into ourselves from the outside." Prati is a preposition meaning "against" or "away." — Swami Shivananda