It can often be a tedious grind: travel, timezones, etc. -- all in exchange for a fleetingly brief speaking slot somewhere. It might look glamorous to some, but it's not.
The travel certainly isn't fun. The presentation itself isn't particularly fun after you've done it 20 or more times.
No, the best part for me is that zealot moment -- when people come up to me after the presentation, and we end up having a really great conversation.
And that, if anything, makes it all worthwhile.