Lowell Little:
Two of the most valued qualifications possessed by the successful French Horn player are flexibility and elasticity of the lips and the ability to support a free-flowing, sonorous tone with the breath in all registers. It is through the development of these qualities only that endurance (the ability to play for long periods of time without undue fatigue) and a pleasing, musical sound may be achieved. […] These qualities can be achieved only through diligent, daily, concentrated practice toward developing a relaxed physical attitude, free from force or strain. page 2
Practice Planning, Logging and Note Taking