If you find yourself checking the countdown on your exercise machine continuously bring some masking tape with you to the gym and put it over the countdown. Your workout will go quicker if you stop counting the seconds and you'll find you can go further than you thought.
When your cycling up that hill or finishing up on the treadmill and it starts to hurt use your mantra. I tell myself, anyone can do anything for (x number) minutes. It really helps me keep going when I might otherwise quit!