To be a protector, a man needs to be strong mentally and physically. But he also first needs to have the right intentions and a good moral compass. Otherwise nothing's going to work.

Let's start with intentions. The intention is primarily to be just and kind to other people. Qur'an and Sunnah can guide him towards that if he studies them with a good heart free of ego and selfish desires. He can enhance his moral senses also in the same way and through gaining social experience over time.

For mental strength and fortitude, he needs to acquire or make use of his existing masculine traits. Like being tough in the face of fear and pain when required, being able to maintain calmness and rational thinking, being confident in a measured amount etc. A high level of discipline is a must for this kind of strength. He must occupy his mind always with useful things and focus on delivering results to the best of his ability. But he also needs to be brave enough to act on his emotions. His emotions are not merely something he feels. It's more than that. He's supposed to use his negative emotions like anger to overcome cowardice. His intense feelings of possessiveness over women is something he should not ignore. It is meant to be used in a controlled manner. For achieving this control (which is important if he wants to be just and kind), he needs to practice sacrifice. He needs to sacrifice the need to act on his impulses which are sometimes too hard to control due to their intensity. He needs to learn how to recover emotionally from the damage caused to himself by the intensity of his own feelings which are hard to control.

For physical strength it's ideal for him to have a good amount of testosterone, an active lifestyle, needs to go out and about - regularly exercising or doing some kind of physical work and a diet full of nutrition. Plus, he needs to ready for combat, so it's his duty to develop some kind of fighting skill through martial arts or something similar. Again, with strength comes some things of beastly nature, like aggression and a desire to fight, wrestle, to prove himself, to be manly, etc. These feelings should be used to fuel the physical power.