I find that things very rarely go as planned. My experience with triathlon fits that feeling very well. We've all gone through the mental struggles associated with the creeping up of the first race of the season ... well I think we all have.
Have I trained enough? Am I strong enough? Can I actually do this? Do I even want to do this anymore? Why am I doing this? Maybe I should just wait until I'm more prepared for the next race?
If you don't go through the mental agony associated with the above, well, good for you. Aren't you fucking lucky.