Currently I struggle with this same thing. Finishing strong. Staying dedicated and purposefully, keeping my mind focused and not passing the buck. I'm talking about my last few weeks at work, before we move. My whole self just wants to check out and get moving! But I can't do that. God has challenged us: "Work willingly at whatever you do, as though you were working for the Lord rather than for people." (Coll 3:23)
I truly long to do this. To be able to accomplish more in the last few weeks than ever. How cool would that be. Kind of like - what's to lose? Not my job!
I want to be able to say like Timothy:
"I have fought the good fight, I have finished the race, and I have remained faithful." 2 Tim 4:7

But the point is, I do not want to become a weight around my coworker's necks. I don't want to cripple this office simply because I can't focus on anything but leaving. But it is truly a struggle. It's so easy to pass on the tough customers and focus on getting all my stuff done so I can just leave. Ugh. I sound so dispicable right now. The reason I am writing this is hopefully to encourage someone.
It is so difficult to work a job day in and day out. It can get so monatinous. It can start to bring you down. But those reminders from God, go to work for me. Do a good job, for me. Maybe you won't rescue a villiage in Uganda from disease or starvation by sitting at a desk. But maybe you will encourage a person who is at the end of their rope. Maybe your friendly sincere quesiton of "how are you today?" will give someone a smile and the knowledge that they are not ignored. I really feel that God has given me this job to teach me how powerful the small everyday interactions are. How they are just as important as my trip to Africa. People, no matter where they are or what they do or what they have, are all starved for love and affection. God longs to impact those around us by our actions. I've been feeling challenge lately to work hard, to finish strong, to make an effort and and impact even though I am leaving soon. I can still be effective.
So, I challenge you to adjust your outlook or attitude. Just try it for today. Maybe something will happen that will make you take notice. Maybe the fedex lady will fall out of her truck and limp to deliever your package and you'll pray for her leg. Maybe she'll beam and say thank you. Just try working for God, try doing whatever you do to bless Him or to express Him to others. I'm trying it, you should too.