Summary: You become more dominant and confident. A great time for ambition and taking initiative. Be cautious with impulsive actions. Difficult aspects may make you appear aggressive or selfish.
This interpretation is for when Transiting Mars is going through your natal first house.
With Mars in this house, your personality is much more dominant than normal, but you are not interested in having great power over others, unless they try to dominate you. You feel perfectly happy to be free to do what you want, and to be recognized as an individual by others. Ambition and professional impulse are stimulated and you have more initiative and self-confidence.
You will want adventures and will be more impulsive. It is very favorable for physical exercise, if you observe the safety rules. Now is the time to show the world what you are capable of doing. In other words, others will be impressed by you. If transiting Mars forms difficult aspects, your approach will tend to be aggressive, self-assertive, egocentric and selfish.