In my first yoga session ever, some time in 2006 or 2007 in London, the teacher began with what looked like an amazingly simple pose. It was the so-called Mountain Pose. All it requires you to do is put your feet together and stand upright. You stick your chest out, pull your shoulders back and keep your chin straight. We were supposed to do this for a couple of minutes.
I have been doing sports for many years, which meant that at this point in my life posture was no longer an issue for me. However, the same was not true for many of the people around me. For some, ADHD probably made the Mountain Pose even more challenging for some, but the main issue was of a different nature. Some girls were complaining that it was "difficult" to stand still for so long and keep the balance. One guy had to remark that his shoulder would hurt, and finally someone complained that it felt "unnatural" for him to stick his chest out. It was a pretty average beginners' class.
Our teacher took a long hard look at us. If he thought that some of us were pathetic, he surely didn't let them notice. Yet, he reminded us that modern life was "unnatural" and would lead us to "get out of touch with our true self". This is typical yoga new-age mumbo jumbo. But then he said something I found quite impressive:
"All I am asking you to do is stand tall, like humans are supposed to stand. If this is difficult for you, then you might want to think about how, quite literally, move through your life."
Here's a video of the Mountain Pose:
I remember that you'd have to put your feet close together, but either way should be fine. Just take a few minutes and follow the instructions in this video. If anything about it feel "unnatural" to you, then you may want to work on your posture. This is indeed how you should stand. Don't slouch through life.
Posture alone won't make you attractive to women, or catapult yourself into a leadership position. However, bad posture is universally unattractive, and when I look around, I get the impression that some people are completely unaware of how bad their posture is. It's relatively easy to fix.
As long as you don't feel fully comfortable with this, admittedly very basic, exercise, then I can only recommend you to keep practicing it. The time commitment is insignificant. Quite possibly it'll be zero. Just do it the next time you watch some silly cat video on Youtube, for instance, or when you're watching a sizzling steak in the pan. Within a few months, at the latest, any issues you might have had with your posture will probably be a thing of the past.