Begin by answering the question, “To whom are you writing?” (Notice I didn’t just write “I think the answer is…,” because the context makes it clear I am speaking to you.) In the parenthetical sentence “you” and “I” were necessary to identify who was speaking and to whom.
I try to not worry much about stylistic preferences when writing in my journal unless I know I’m writing in hopes of a particular audience reading the content in the future. In some cases that future audience is me, so I’ll use the word “you” unless I’m trying to convey a present state, like “I’m feeling optimistic about completing _______ today.” In some cases I am making a statement that I hope my grandchildren will someday read, so I use “you” or “we” as a general pronoun.