When you have those moments where you do actually get things done, are you still focusing on the mundane tasks? That might be why the inspiration isn't lasting. Set aside a small amount of time each day to work on some creative task. Don't obsess too much over picking something really impressive or useful; start small. Stick with it, and eventually you'll find yourself more energized toward everything else.

"We should be taught not to wait for inspiration to start a thing. Action always generates inspiration. Inspiration seldom generates action." -Frank Tibolt