Transitions begin with an ending and end with a beginning.
I ran across this idea as it relates to career changes (not mine, btw!) and I have been thinking about it in relation to the transitions we ask our horses to make while performing. This compliments the idea that verbal instructions are more about *changing* what is happening than about the end result. Saying "Trot" isn't as much about Trotting as it about changing ....transitioning ... to the Trot from something else. Something must end before something else begins. Maybe thinking of it this way will help organize all the micro events that must occur in the right order with the right timing to accomplish something seemingly so simple as a transition from one gait to another.