First of all, your roommate is more masculine than you. Judging from his appearance, he should love you and feel more secure than you. So you need to get rid of your thin appearance. You can choose to go to the gym or exercise with your bare hands in the street. Exercise for an hour every day and eat properly, and you will see your changes in half a year. I was thin and insecure before exercise, but now my girlfriend says that her hands are thick every time she holds hands. So appearance is the first step for you to become a man.
Then simply change the dress, you can try a dress style, for example, if you like transportation, you can start to take a mature route or yuppie style, which will be more mature and stable than sports style. I have a roommate, a hunchback, who wears leather boots and rhubarb boots every day, which makes people feel very man. So these are some relatively simple ways to change.
Similarly, if you want to be a man, you can't just look, because when you meet something, only a man with personality and heart can make you dare to take on and stand up. This is a real man. So you should have a strong heart and don't be afraid of things. This requires reading more books at ordinary times, and then doing more economic things, so as to be mature and steady. And get rid of some childish habits and learn to control your temper, so that people can feel safe.
However, people are different. What suits you is not necessarily a man's personality. Everyone should have their own personality to be interesting. You can be warm without a man, which is also a very likable character. I used to think that other people's personalities were biased and liked to imitate, but when I grew up, I felt that my personality was the best. I just need to get rid of some shortcomings. After all, there are still many advantages.