As a musician, I'd like to be remembered for the notes I didn't play.
One of my favorite jazz bass players, Ray Brown, used to say that a bass player's job was to make the rest of the band sound good. This is easier said than done, though a musician of Brown's stature makes it sound simple.
That's because simplicity is one of the keys. Forget the lessons, the practice, the memorization, the monster chops. Just because you can play it doesn't mean you should. A powerful musician holds back. Think Neil Young, or Paul Desmond. When one note will do, play one note. Don't flood the sound canvas with color. If you mix too many colors you get brown, the color of mud.
I recently finished a recording with one of the bands I'm in, and in the process of mixing down a recording you hear the songs many, many times, until you know every single note and nuance. I try to keep simplicity as my mantra in the studio but in the playback I can always hear notes I didn't need to play. With modern recording technology you can "zap" anything you don't like from the mix, but the producer of this effort doesn't like to do much of that as it can sterilize the spontaneity. So I hear the excess notes, over and over, and give myself a mental kick in the shins.
Music without space is like Swiss cheese without holes. Listen to the 14 year-old shredders on YouTube who have mastered every known Stevie Ray and Jimi Hendrix lick and can play them at 78 rpm. It's impressive, but somehow it feels more like an act of aggression than music. Yes, I'm sounding like an old fart, but the greatest young musicians usually have an 'old soul' maturity about them; think Johnny Lang, or Joss Stone. They know when to take a chance and commit to a single, strong, pure line.
The other key is listening. It's critical, in most types of music, to listen to what the rest of the ensemble is doing, and in improvisational music such as jazz or rock you get much of your inspiration from subtle cues from the other players. In a great band sometimes nobody's driving but the bus gets there just the same.
Leave a little space. Leave some extra room between you and the car in front of you on the ride home. Turn the radio off while you dress in the morning and just listen to the sounds of your house. Close your office door, close your eyes and breathe.
Inspiration will creep in.