I meet this sentence in the first page of one book:
To Keith - always part of what I do.
What's the meaning of "always part of what I do"?
It means Keith has made a profound impact on the author's life, to the point where, in just about endeavor the author strives to accomplish, Keith's influence can be felt.
As an example, if my father passed along a good work ethic, taught me how to treat people well, and taught me right from wrong, and then I went through life trying to adhere to those principles, then I could say that, day to day, my dad is "always part of what I do."