being aggressive may not be bad

not sure if this relates to u but only my 2cents: u have to know what is achievable and what is not and get support from the management.
Often times, people don't want to do in ur way because he/she is not convinced your idea will bring enough value or on the highest prority. You need to be "Assertive and Persistant and Polite". I have seen 2 people in my past company got canned because they are too aggressive, 1 VP and 1 director, neither got enough support from the high-up. They both are very smart people, but do not fit in the culture, nor reach out enough to the team members who r close friends of the existing management.