While practicing, you are relaxed, aligned, your movements are smooth, deliberate. In other words, you are actively maintaining your tai chi composure.
The question is, when do you stop?
Do you turn your tai chi on when you practice the form, and turn it off when you stop? Do you turn it off when class is over? Or when you get interrupted or distracted?
Why turn it off deliberately at all? Why not at least try to keep it on all the time?