When you were born, Mars, the Planet of Action and Assertion, appeared to be going backward in the sky, against its usual direction. As you can imagine, Mars does not particularly like to be retrograde! Its forward energy turns inward instead of outward.
You, too, may find that asserting yourself is not as easy as it seems to be for other people, and you can become rather envious of their ability to go after what they want. You may not necessarily be shy, but when push comes to shove, you're not the best at sticking up for yourself. You have an easier time acting on behalf of another than you do stepping up to the plate for yourself. Mars is related to anger, too; with this planet retrograde in your chart, you won't necessarily be slow to anger, but expressing it can be a problem. You're likely to sit on it, letting it stew and simmer and strengthen until it comes out in a torrent due to some unrelated trigger, or until it gets replaced by anger at something else. You tend to implode rather than explode. The proper use of assertion and aggression will be a lifelong lesson for you.