Pencil exercise

I started the pencil exercise today. The corners of my mouth feel a little sore so it must be doing something. Anyway i am following these rule i got from a post by Eric Bolvin on the Trumpet Herald forums.

"I've developed a number of techniques for practice that involve the pencil exercise. You should follow the instructions implicitly.
Guidelines:
1. Always practice the pencil exercise at the very end of the day. At this point you have no more playing responsibilites. I usually do it before going to bed.
2. Always follow the pencil ex with a session of lip flapping, at least 30 seconds. Cupping your hands around your face will help to get the flap going.
3. Play by the rules. Hold the pencil for one minute ONLY for at least two weeks. It doesn't matter that you can hold the pencil for ten minutes. This is not a competition.
4. Increase your time to two minutes and then three minutes. If you're hurting, then limit your time. Although the facial area is muscle, it's muscle that is in balance and can not grow much.

Use these guidelines to help you with the pencil exercise and you might see some favorable results in your playing.
If you don't see results, then you've learned something and you can apply it to your teaching,
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Eric Bolvin