Sun Square Mars in Depth
Ninety degrees of friction
Sun square Mars puts your identity and your drive three signs apart, sharing a modality but nothing else. Both want to lead in the same style and refuse to lead in the same direction. Standard orb is six to eight degrees. Where the conjunction fuses will and action, the square makes them rub, and rubbing produces heat and also produces polish.
This is the classic athlete and entrepreneur aspect, which is the same thing as saying it is the classic aspect of people who cannot stop competing even when nothing is at stake.
The specific pattern
The signature behavior is effort that exceeds the requirement. You push harder than the situation calls for, then feel obscurely cheated when the result is the same as it would have been with half the force. There is usually a running argument between what you want to be and how you go about getting it, so your methods keep undercutting your image. The person who wants to be seen as calm and authoritative but gets there by out working and out arguing everyone is the standard case.
It also shows up as picking fights sideways. Rather than confronting the actual obstacle, you find a nearby one that is safer to attack. Recognizing that substitution is most of the work.
Natal versus transit
Natally it is a permanent engine with a permanent misalignment. By transit it is short and sharp. Mars squares your natal Sun about twice in every two year cycle, holding orb for four or five days, and those windows are famous for accidents of haste, cutting yourself in the kitchen, sending the email, saying the thing. Nothing mystical is happening. You are simply moving faster than your attention.
The transiting Sun squares your natal Mars twice a year for about two days, which is a milder version and mostly registers as impatience with other people's pace. Both transits are best used for physical work, where haste costs you nothing and effort is the whole point.
What growth actually looks like
It is not calm. People with this square who try to become mellow usually just become resentful. The functional version is a life with enough legitimate resistance in it that the drive has somewhere to go. Hard training, demanding work, competitive hobbies, a craft with real standards. Give the aspect a worthy opponent and it stops manufacturing unworthy ones.
The reliable change with age is aim. At twenty the force is everywhere. At forty five, in the people who have used it, it is pointed at two or three things and is formidable. This is a pattern to reflect on, not a diagnosis, and persistent anger that damages your life is worth discussing with a professional rather than a chart.