Cziffra, I've gone through that period in my life. I guess it depends on what your personality is in the first place. I have a personality that is very adaptable, so basically when I practice I feel as if my personality is infiltrating the music, and usually by the end it's all me:) (well... not all me.. mostly all the composer, but through my head). Also, I suppose if a person always practices, then the more they practice, the more they are themselves.
I don't find playing to be an energy boost or a spiritual drain. When I practice I think of it more as finding something within myself. Often after I practice I'm in a very pissy mood, and it takes a lot of mental energy to respond to somebody in any kind of a pleasant manner, but for me, that's just another side of my personality. It's all me baby! hehe
anyway, what I'm trying to say (rather unsuccessfully I might add) is that don't think of it as a spiritual drain. it's another side of yourself, and another side of a musician. I'm glad that you feel the way you do, because it means you're actually making music. Enjoy it. It's rare for someone to actually make music in this world.
mt