What happens next?

How to be more aggressive
Be assertive in your posture.
You want to appear in control, poised, and confident without looking awkward or uncomfortable.
Approach someone directly, rather than from the side of behind.
Maintain enough distance so you can hear the person but are not in their face. Relax (do not slouch or hunch) your shoulders and spread your feet shoulder-width apart so your body weight is balanced evenly on both legs.