This is the concept of enthusiasm. Enthusiasm is vital to the success of your life. Remember the quote, "if you stand for nothing, you'll fall for anything"? Sometimes you lose your zest for life because you think you have nothing to be excited about. The solution is to inject a little enthusiasm into the many tasks in your day and see if it doesn't change for the better.
I use this technique when running a choir rehearsal on a weeknight. I realize that people have been working all day, and I appreciate that they are committed enough to show up for a two hour rehearsal after a long work day. I know they're tired; so am I! But if I can get them enthusiastic about what they are singing and how they are singing, rehearsal goes from drab to fab, and those two hours fly like minutes!
You can inject enthusiasm into just about any task and make it more desirable to check off your to-do list. Gotta clean the house? Put on some good jazz tunes (or whatever else you prefer to listen to) and double your cleaning as an exercise routine. Need to run some unexciting errands? Envision how you will feel after you've completed them and imagine how the completed tasks will make your life easier. Have to brave the long morning commute? Download some new podcasts to your mp3 player and use your time in the car as "personal development". The fact is, you can turn anything you have to do into a more desirable task if you find a way to develop some enthusiasm for it.
In music, if I'm feeling apathetic about a particular task I have to do (chart a song in a new key, for instance), I first assign myself a time limit to work on the project. Usually it's 30 minutes to an hour. I promise myself that if I can't get into the work at the end of the time period that I can quit for the day and at least I'll have gotten started. But what usually happens is I get into the project and get excited about it and plow through until it's done.
Are there areas of your life that need an injection of enthusiasm? Maybe your singing needs some new life. Try to imagine what the author of the material you're singing was thinking and feeling when he/she penned the words, then try to get in that same spirit. Experiment with different vocal tones and dynamic levels. Research the style of music you're performing and see if you can find out something interesting about it that you didn't know before. Or, go completely off the wall and choose a new piece of music in a different genre than you ever performed before (reggae, anyone?) No matter what you do to spice up the music in your life, taking the time to become enthusiastic about it will be anything but boring!