One of the most important pieces of advice I've ever gotten from a mentor comes from Steven R. Covey in The Seven Habits of Highly Effective people. It would have been worth reading the entire book to learn this one principle (though I did learn a lot more from it).

He draws a square like this:

• Quadrant 1: Things that are important and urgent are the easiest to do. These things include answering the phone, cooking dinner, talking to someone who is standing at your desk, working on a project that's due tomorrow. They get done with no special effort because you have to do them.
• Quadrant 2: This is the important area. These are the things that we've "always wanted to do" or "plan on doing someday" but tend to never get done. This could include learning a language, taking a trip to Europe, kicking a bad habit, starting a good habit, taking a college class, investing in real estate. If there is no urgency to get important things done, a lot of times they won't ever get done.
• Quadrant 3: Things that aren't important and aren't urgent usually don't (and shouldn't) get done.
• Quadrant 4: Things that are not important but urgent could be something like buying a new dvd player, seeing Lord of the Rings or other things that we want or feel we need to do but aren't really important.

The way that I've applied this advice is by making a list of things that are important but not urgent and putting it in a place where I'll see it over and over. In my case it's in the front of a notebook I use for journaling and writing down ideas. I review the list every few days and rewrite it entirely ever few months to make sure it's still aligned with my current goals. It has proven invaluable to me.

By focusing specifically on these tasks and making an extra effort to accomplish them, I feel I've made more progress over the last year than I made over the last several years previous.