Planets / Mars
Personal
Mars governs the energy of action, desire, and the capacity to assert oneself in the world. It's the planet that drives someone to pursue what they want, defend what's theirs, and compete when needed. Without a reasonably healthy Mars, it's hard to set boundaries or hold one's own ground under outside pressure.
Mars's sign in the birth chart describes a person's style of action: how they fight their battles, how they pursue what they want, how they express anger. A Mars in a Fire sign acts fast and impulsively; in Earth, with patience and method; in Air, through words and strategy; in Water, with emotional intensity.
It's also closely tied to sexual desire and libido: together with Venus, it describes much of a person's style of pursuit and desire in matters of love.
The god of war: action, desire, courage, and also aggression when that energy finds no constructive outlet.
Gives courage, decisive capacity for action, and an ease for defending what's yours without guilt.
Can translate into impulsiveness, trouble controlling anger, or the opposite: difficulty acting and asserting oneself when needed.