Write much and write often

An exceelentay post on Craigharper.com on public speaking.

His site: http://www.craigharper.com.au

Gives tips about speaking and I particularly like this practical advice;

Spend significant time writing, preparing and committing your presentations
to memory. You need to (1) have great content (fresh, interesting, challenging,
stimulating, confronting, funny, relevant) and (2) you need to know your stuff
inside-out.The better you know your material, the more relaxed you will be in
front of your group.Looking at notes repeatedly while you speak... not
cool.

I struggle to come up with interesting material. Now Ive been wanting to write blog posts regularly, but even when I intend to write something I struggle to come up with ideas.