The people who are disciplined about their workouts and those who struggle to get their butts off the coach are not very different. Both will have times that they don't look forward to their workout. It is just those who are able to get up and out find some sort of internal motivation. For me, I make a play list on my iPod, filled with songs that will help me as I go out to remember why I'm doing it in the first place. Here is my suggestion of 5 songs that will help motivate you to get that workout done!
1) "SexyBack" - Justin Timberlake (not necessarily motivating lyrics, but a great beat),
2) "Suddenly I See" - KT Tunstall,
3) Pharcyde - Runnin' (I think the title is enough of a description),
4) Such Great Heights - Postal Service,
5) "Canned Heat" - Jamiroquai (oh man, I want to dance thinking of this song!).
Of course, these are just suggestions. Find the music that motivates you and look at your workout as a time to get away and listen to the music you love.
Also consider (for your completely random, inspiring mix) ...
1. Get it Started - Black Eyed Peas
2. Dancing In the Dark - Bruce Springsteen
3. Hips Don't Lie - Shakira
4. Dirty - Christina Aguilera
5. Danger Zone - Kenny Loggins
Be sure to crank it up and sing at the top of your lungs. I think it's important to prove to everyone you have plenty of lung capacity while working out.