I don’t think you’re going to like today’s point. I don’t like it very much myself but it’s got to be done. For most purposes, when you give a presentation you should stand. Not clutching the back of your chair for support, not leaning against the podium but two feet on the floor facing your audience.

There are times when sitting is right. When it’s an informal discussion, for example, where everybody is to contribute. But most of the time you need to stand.

You can move around the room. This has the simple effect that people will look at you, not shut their eyes and drift off
You can make eye contact with everybody
You can reach all your props and teaching material easily
You’re involving your whole body in the presentation. Many people think this makes it more memorable.
You’re sending out the signal to the participants that ‘this will be short’. Only a few self-obsessed people stand up in front of audiences for longer than they need to. And you’re not one of those, are you?
The worst part of standing up is the actual standing up. Most people don’t feel at ease as they get out of their chair and walk forward to their speaking position. Here are a couple of tips.

As you’re waiting, keep your feet flat on the floor. Don’t have them crossed. Trust me, getting up and walking will be so much easier.
Decide in advance where you are going to stand. Focus on that spot
Walk forward briskly and confidently
And that’s how you become a stand up sort of person.