What is the difference between Sun and Mars vitality in relation to the physical body?
And to what extent can free will/physical training trump the negative state of these planets?
There's a lot of very prominent athletes with Sun in Libra which you'd think would reduce their ability to perform but many are literally at the top of their game.
For example, Anthony Joshua is a two-time heavyweight world champion boxer with both his Sun and Mars conjunct in Libra.
In general, by what % does free will matter in comparison to the natal planetary energies?
There are plenty of athletes with a Libra Sun... because athletes are typically coached or henpecked for this since childhood, and it's usually the father.
Joshua's entire distant family are boxers. When he went to Nigeria he was beaten constantly. His male cousins got him into boxing, and they would try to beat him up. He also got into a major gang and ended up in jail.
This is a tough guy, yet the Sun Libra masochism and obsession with fitting in is still there. Whose will at core is at play here? Their own or others? He also credits becoming a famous boxer to having a formidable team.
Libra has a side to it that represents higher command and even combat, enemies in life as well. It is the most misunderstood sign of the entire zodiac and IMO, cookbook astrologers really don't understand well how it manifests in men, nor do they understand why it is a masculine/electric sign despite being of Venus.
The reason why this brings problems with the Sun is that all of this can interfere with real individuation, like being a puppet on a string. Many Sun Libras get into trouble with marriage, romance and sex for that reason too... I have seen that time and time again, more common than the violence scenario.
You cannot just assume that because the Sun is domiciled in Leo that Leos would do the best in all positions that the Sun rules, or that all boxers have Mars in Aries or something. Every Chart is a composite of energies plus exertion and will.
Compare AJ to a typical Sun Leo celebrity like Madonna or J Lo, who jumped from person to person and team to team to make themselves famous and burned every bridge, because Leos cannot tolerate non-subservience. Both of them became famous later as well, past 25, because the idea of being controlled is repulsive to any true Leo, but that's not necessarily conducive to being famous as rapidly as possible.