Best man speech

I have to write a best man speech for my brother but it's been so long since I wrote anything serious. Whenever I do write things it's just for fun and even though he said the speech is optional I genuinely feel like I've got a million eyes on me. I've been rewriting the same speech then erasing it and it does sound pretty decent but it also sounds like I'm demanding the audience feel emotion. It goes to emotional places quickly and spends a long time there. I've got over a month to work on it but like, blegh, I feel sick because I don't want to mess it up