However, he wasn't the best presenter and he struggled with projecting a dynamic stage personality. He was smart enough to realise this and regularly tried working on it during his talks.
But inevitably towards the end of his speeches he would wind up an apology for his mediocre performance. He did it once, twice, and after the third time someone finally told him to stop apologizing:
"Remember that no one thinks your speech is quite as horrible as you do. If you're going to keep apologizing for your 'poor performance' you create an unnecessary negative perception with the audience. Most of them probably did NOT think your speeches are poor, so don't draw unnecessary attention to your weaknesses."
That's good advice that I would give to any aspiring or novice public speaker. Your first talk is not going to be as great as you probably would've wanted it, but you should never draw attention to that fact (during the speech I mean, its okay to do it afterword when looking for feedback).
If you make mistakes due to public speaking nerves, if you struggle with content, get your slides mixed up or stumble over a sentence or two, don't draw unnecessary attention to these things by apologizing for them.
Of course, some things deserve apology: An example of which jumps to mind immediately, is that of being late. If I start a talk 10 or 20 minutes after I'm supposed to, I'll always apologize for the inconvenience this might have cause. (For many reasons, it's always a good idea to arrive early!)
As with all things, use your common sense, but it's definitely not necessary to apologize for every insignificant little error that will inevitably make their way into your presentations. Pro's don't - they just gloss over them realizing that nobody is as critical as the speaker himself.
Apologies have their place, but they can easily become an escape hatch for people new to public speaking. And Public Speaking Nerves will often lead your to open you talk with a disclaimer. The reasoning being that, since you believe and know that your speech isn't going to be that great you might as well alert the audience in advance, that you "really aren't very good at public speaking".
Ever heard that line? I sure have, and its a brilliant and effective way to lower the expectations of your audience and set yourself up for a mediocre performance.
I'll argue that you should maintain the focus and energy of the crowd on the topic you're presenting about, by not drawing attention to unnecessary things, such as your own mistakes or (perceived) sub-par performance.
I had a friend who was fairly new to public speaking, but had been given the opportunity to give 20-30 minutes speeches in front of about 100 people every now again, usually once a month.
Now my friend was one of those speakers who put together great content - his speeches by themselves were good to listen to and had informative and well-researched content.
Don't make a habit of using this word too often from the stage...