Long post follows, but very informative.
Presence as the word means is to be present, not just physically but also mentally. Practically that means actually paying attention to the current situation in real-time. To be specific you gotta pay attention outside yourself, not too much to what's happening in your head. In a conversation you listen attentively and do your best to understand what they're trying to express. Don't fully understand? That's a good basis for a detailed question, fire away and don't evaluate the question too much. That's showing real interest since it shows you really listened and care enough to ask based on what they said.
In group conversations you might have to be a bit more aggressive and unapologetic. Still listen carefully and understand the subject. Try to relate it to personal experiences or knowledge, if you get a spark of being reminded of something then don't hesitate too much. Inject your statement or question into the conversation, you have to actively participate to get attention.
However do NOT make a lot of assumptions, guesses or say things you can't be relatively confident to be true. It's important to have people trust you to some degree, you must give off that you can be taken seriously to be respected. As
@wifehunter suggests jokes
are good and it serves to make people ease up a bit, but too many makes people not take you seriously. It is as
@Atom Smasher says really important to be in control, you'll automatically seem like you're in control if you actually are. So don't bother trying to act all confident and sh!t if you're not, rather work to build up your knowledge and experience and the rest will follow.
Being of value to others means providing something of value to others. I'm not talking about money now, money doesn't ultimately solve problems, the one's paid to solve problems provide the actual value worth paying for. So what am I getting into here?
Experience and knowledge. Experience is basically knowledge that you've attained on your own. Knowledge in this context is experiences shared by others. If you pay close attention to pretty much everything going on around you (being present) you'll learn a whole lot more than those who don't. Your experiences are valuable to those who doesn't pay attention to their own, you can convey what you've observed. Ranging from funny sh!t you see on the street in everyday life to major discoveries that can benefit humanity. Do you see how this is a massive advantage?
You'll never run out of things to say about interesting things you've experienced or seen. You'll be a resource (magnetic) to other people since you notice things they miss and you probably know something about it. You actually know with confidence what you're talking about, you did after all witness it first hand so no need for cheesy jokes that everyone has heard before. People will be interested if you frequently experience new things and explore what's around you, everyone's curious about what other people do that they haven't done. If you have a lot of experiences in a broad range of things it's easy to come with something to share in pretty much any group conversation. Since there's actual substance to it not only will you become more present and noticable, but they'll let you continue to dominate the conversation because they're genuinely interested.
Your height won't matter at all. I've seen lots of people with different shapes and sizes completely consume everyone's attention, because of how they share experiences. They provide value and make themselves more valuable by listening to other peoples experiences as well.
Basically this is the long detailed version of "embrace life" and "knowledge is power".
