I find myself in a similar situation. I make money purely on how much work I do, so every hour that I waste at work is money I could have earned but didn't. It's very de-motivating. When you figure you "lost" $500 in a day by being a slacker, it's hard to get excited about saving $10 by not going out to dinner that night.
Here's what I've fround. My motivation and energy for work comes in waves. I just have to ride the wave when I'm feeling motivated and energized to get a lot done, and then survive the ebbs. With that being said, a job change about two years ago, doing roughly the same thing as my old job, did result in a positive attitude adjustment. Although I still go through low ebbs, it's more 25% of the time that I feel down about my job rather than 75% as in my previous job. But the low energy periods still come (especially in the summer!) and I use it as motivation to achieve FI. One day I'll be able to spend more of my days doing what I want, based on my energy levels and interests, rather than having to drag ass into work when I really don't feel like it.
I've also found that controlling my work environment helps. If like me you spend too much time surfing the net, you might find that working offline if at all possible can help your productivity. Sometimes I just go into a conference room where no one can find me and get shit done. I once left work to go to a coffee shop, and the change of place made it possible to focus when I had been unable to look at my computer screen for more than 2 minutes at a time while in the office.
Good luck!