If you have Mars in retrograde in your natal chart, you may find that you are waging an internal battle causing you difficulty in asserting yourself because you are afraid of the consequences of releasing your anger. You may tend to over think before you act. You may find that you have a tendency to hold back. In karmic terms, you are likely to be attempting to make up for some vaguely recollected but deeply influential past misdeeds you now regret. Whatever the cause, you are holding yourself back instead of standing up directly for your own interests. This works directly against the life lesson that you are here to accomplish. You are learning about yourself, defining who you are by what actions you take. You will need to let go of timidity or a lack of direction in order work out how you can initiate actions without creating the chaos of needless destruction.
I found this interesting, hope it helps more:
If you have Mars in retrograde in your natal chart, you may find that you are waging an internal battle causing you difficulty in asserting yourself because you are afraid of the consequences of releasing your anger. You may tend to over think before you act. You may find that you have a tendency to hold back. In karmic terms, you are likely to be attempting to make up for some vaguely recollected but deeply influential past misdeeds you now regret. Whatever the cause, you are holding yourself back instead of standing up directly for your own interests. This works directly against the life lesson that you are here to accomplish. You are learning about yourself, defining who you are by what actions you take. You will need to let go of timidity or a lack of direction in order work out how you can initiate actions without creating the chaos of needless destruction.
from sky view zone