I never had a problem expressing my feelings because I am secure in myself. Men who fear showing their emotions tend to be young and insecure. Young men get fed so much bullshit about how they should live their lives and carry themselves from all angles.
You have the "progressive" and feminist types try to shame you for being a man and they try to pretend that it's some sort of defect to overcome. The "macho" and misogynist types try to convince you that your gender is a point of pride and that you should double down on the stereotypes they approve of. You have the "traditional" types that try to instill the idea that being a man is a like a job with specific roles that you have to fulfill to qualify. There's many more types, but the point is that you're getting constantly bombarded by all these nonsensical, contradictory, and misinformed ideas about how you must live your life. It's not wonder young men are having an identity crises.
In reality, all these people are full of shit. Masculinity is not a role and it's not a stereotype, it's a state of being. You're masculine because you are a man. Everything that you do is masculine because that's what masculinity is, it's the behavior of men. You being yourself is masculine. There's no need to live to some misguided ideal or rigid standard set upon you by others. You're masculine whether others approve of it or not.
As it happens to be, men are humans, and humans have emotions. It is perfectly natural and healthy for men to express their emotions as they fit. If you're sad cry, if you're upset be mad, if you're filled with joy then be happy, if you're anxious then be afraid. There's no shame in expressing yourself or being vulnerable. These are things that make people interesting and deep. If someone takes issue with that then they're the ones with the problem, not you. If someone can't handle you for you then they're not even worth your time. At least that's how I see things.