Doing fewer things--and doing them better--is profoundly important.  There are so many things to do, but usually only a handful really matter. Those are the things that require intense focus and exceptional execution.

Said another way ... 

Cut Things You Don't Care About, Focus, and Be Awesome

There is no better way to put this in context than to consider our own mortality.  Steve Job's 2005 Stanford Commencement Address, and Merlin Mann's recent blog post titled No One Needs Permission To Be Awesome, do an excellent job explaining this.

Your time is limited, so don't waste it living someone else's life. Don't be trapped by dogma, which is living with the results of other people's thinking. Don't let the noise of others' opinions drown out your own inner voice, heart and intuition. They somehow already know what you truly want to become. Everything else is secondary.

The most essential step in doing the things that matter most is Focus. Focus on the things you care most about. Focus on the things that, once started, are hard to tear yourself away from because you are so passionate about them.  Doing this requires cutting the other distractions, and many of them are not easy to drop.  Some tough decisions need to be made.  

How many things do I need to shed, cancel, defer, drop, shank, or shit-can with extreme prejudice in order to singlemindedly focus on this one thing that I love?

Another Merlin Mann post puts it very well: First, Care. Once you know what you really care about, you can figure out how to focus on them. It makes it easier to settle hard decisions and drop things that would otherwise seem undroppable.  

There are some great resources out there that provide inspiration.   focus : a simplicity manifesto in the age of distraction by Leo Babauta is a great book, and most of it is available freely via the web.  

Finally, I'll end with some words from the ever-quotable Seth Godin:

There’s not much more important than focus and tenacity. I think that making the choice to do art, the choice to make a difference… do that and add focus and tenacity and you win.