To me, flexibility means have the means to do what you need to do, when you need to do it (on the horn). High register, low register, loud, soft, etc. It’s like stretching for an athlete - you can’t just start running hard and expect the optimal results without first preparing your body for action. As brass players, we can’t escape flexibility exercises. 
However, it sometimes can get monotonous to play the same exercises day in and day out. So here, I’ve included a couple of exercises that will give you some new challenges in your daily flexibility practice! 
See you next time -