I grew up tuning all my scales with a tuner using Difference Tone Tuning something I learned from my teacher Albert Tipton, Principal Flute of Detroit and St. Louis Symphonies. I just posted on my Instagram account a simple exercise to get back in shape quickly as it strengthens the tiny muscles in the upper lip.
Hold the tuner on the 5th scale step. Then play the scale, no vibrato, at a mp dynamic. At the end of each scale step, play either the 5th or the tonic an octave higher, and play a diminuendo to ppp as demonstrated below:
In the video, I told people I would email the exercise, but after so many requests, I have decided to lead everyone to my site.
This is a preview of the Morning Exercises book I have compiled that should be available for purchase soon.
Here is the Instagram post: