yeah you may be discouraged when competing with other people, but when you compete with yourself, you almost always win - at least, as long as you're faithful to your training.
It's so awesome to see progress in increased speed, increased mileage, less weight etc etc. That's enough to encourage me to keep going at it!
Just one month ago, this wimpy little hill would leave me panting and gasping for breath at the top... now that hill is like nothing to me!