Wedding speech worries - what do speakers fear most?

Wedding speech worries - what do speakers fear most ? I run a thriving voice coaching business based in the UK. One of the most popular services I offer is one-to-one voice / performance coaching for anyone who has been asked to make a wedding speech - from the Best Man through to the Bride or Groom themselves. I not only help clients to write their own speech but mainly how to actually perform the speech with confidence and panache and how to eradicate "stage fright." My question is this: what does everyone think are the most common fears that people have when asked to make a wedding speech? I've come across a lot of different reasons for nerves associated with speaking in public but I'm discovering that it's an extremely common problem with Best Men in particular and one which the potential speaker will often keep from the Bride and Groom and the rest of the wedding party for fear of adding to the general stress of the wedding itself! This wonderful new online community is a global one and I'm curious to know if the problem of "wedding speech nerves" is indeed an international one, or is it just the British who get the jitters when asked to make their speech? (Obviously I suspect the problem is not just limited to us Brits, but I'd love to know what people think!)