In my philosophical contemplations I have discovered a possible common trait for all masculine people, even if they're females (as females can be masculine as well): it's the ability to last long and endure while remaining resilient while whatever opposition, from temptation to offense, is encountered. Thus, I would define masculinity as a merit, as the talent of lasting longer while remaining resilient. The original books I wrote, by the way, include the expression "be alone while together", AKA, keep your individuality while you're amongst the company of others, whether they have a herd mentality or not. That, too, can be seen as a variation of the definition at hand.
This masculine principle exists in many areas: from to sexual relationships to competition, to physical activities, to reputation, to combat and so forth. Arguably, it can exist in anywhere there is a form of opposing energy or entity; an opposition which requires a long-lasting endurance.
Theoretically, the expression "take it like a man" is just that – "swallow" and endure whatever has been received by your senses. It's exactly why a lot of people, both fictional and real, are seen as manly due to their above-average ability to "take" things "like men".
And, for a more obvious examples: in sex it can mean the lasting of one’s sexual awakening, in competition - the drive to last the longest. In physical activities - to bear intensive workouts and lift heavy objects for a longer time period; to not get triggered so much by whatever discomfort that was made upon interpersonal interactions, and in combat - to be the less tired and exhausted during the fight, so you'll have a higher chance at defeating the opponent.
As you can see, to be masculine can simply mean to have much endurance and much resilience. Feminine people, on the contrary, could have lower libidos, give up more easily, be physically weaker (although not necessary), be more triggered and take things at heart and/or blowing them out of proportions, and cower in fear in case of danger that they can possibly overcome with enough courage and the drive for defense. Thus, feminine people can be defined as those who have less endurance and are less resilient in whatever area. Of course, they can have other virtuous traits, such as more empathy, a higher sense of etiquette, higher emotional intelligence and so forth. Hence why I'm not saying at all that a more feminine psychology is inferior to the masculine one, as each of them have their strengths and weaknesses, whether they've been adopted/chosen or developed throughout life by different things and beings.
But regardless -- sentimentality, self-pity, delicacy, defeatism, passivity, lack of assertiveness, lack of confidence, lack of motivation - all of these are concepts which hinder our endurance and resilience, and also are adopted by potentially many feminine people, men and women. The exact opposite of these concepts, however, do the opposite effect to us, and could also be a defining component of a more-masculine person.
So, cut off all the hatred and rejection there is to masculinity, and focus on its more vital concepts, both in awareness and in execution - and you could become a stronger, happier and healthier individual. From good physical fitness to a strong determination - masculinity does not have to include crimes against humanity, crimes that were, are and probably will be committed by feminine people as well.
I therefore shall not tell you to “be a man” or “grow some balls”. Instead I’ll tell you, “be more vitally masculine”, and “grow your strength and life-force”. Even if you’re a woman or an old individual - becoming more enduring and more resilient can give you much benefit and happiness in life.
In this day and age where men are condemned, arguably for being masculine, by neo-feminists, let us not forget that masculinity has its own virtues as well.