I wouldn't say I have really bad posture, but it is noticeably not good. Just wondering if anybody has any tips on how to improve posture?

They say to think of your spine as being attached to the back of your head, and not to the base of your neck. Try to elongate that as much as you can. Chin down and shoulders back.

I saw this picture of myself taken at a funeral (of all things). I'm already very tall and skinny, and when I talk to shorter people I tend to slouch to get down to their level. It was from about 30 feet away so you could see my whole body. Wow, it was terrible. So ugly. My head was way foward and lurching forward. My neck looked like a vulture. Then my shoulders were slouched and my whole body had this S-like curve from my spine down to my legs which were slightly bent.

I've been watching RSD videos lately and Tyler Durden has this awesome stance. His knees almost bend backwards, it's weird. But it's the opposite of what I do, and I have terrible posture sometimes. I have this big 7 foot tall mirror in my house now and I practice posing in front of it. That really helps. But you need to see the whole body, not just the upper half in the bathroom mirror. Leg stance is an important part of it too.

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“Nothing is impossible, the word itself says 'I'm possible'!” ~Audrey Hepburn

This is a good description of myself too. Thanks for the advice, it will be helpful.

stop being a lazy ass and go to the gym and do deadlifts and exercises that work out your back, go heavy enough so that you can barely do 6-12 reps but make sure you use correct form or you'll snap some shit up. push ups also help posture as ive experienced it myself, endless pushups and pull ups every week and you'll notice a difference the first week.