Since I am a true novice at going with the flow, there's another saying that strikes me as a useful starting place until I loosen up a bit more. The Ashtanga Yoga practitioners have a very disciplined home practice (or they go to a Mysore-style studio) in which they practice a set sequence on their own nearly every day of the week. One day of the week, though, they "subject themselves to class." This is the language I've heard, "subject themselves."
On a very basic level, I think anyone who has both a home practice and who goes to class understands what this means. At home, I have a tendency to play to my strengths, to not hold poses, to skip savasana, to avoid postures that make me feel clumsy, uncomfortable, or bored. In class, though, you don't have this choice. Someone else is calling the shots and, by gum, you will do Eagle Pose.
Beyond this most basic level, I think being subjected to class and being a student in any realm is a useful reminder that we aren't always in control. Especially for those of us used to calling the shots from the front of the classroom, but for anyone muscling through their "five year plan," subjecting one's self to a class (tennis lessons, art, cooking classes, whatever) can be a sometimes uncomfortable, sometimes liberating reminder that we may be less fully in charge than we thought we were.
The question then is what happens when you're subjected to a class in which not everything unfolds according to your expectations, or in which things happen that you don't like? Hopefully, we can still find it in ourselves to enjoy the class, or to learn from the unexpected. This is why any kind of practice can be useful practice for what we're always subject to--life!