Oh man. This is an epic question.

Wake up early without an alarm, and feeling rested and ready.

Going to the gym (or ballpark, or whatever) and having a better workout than usual, one where you feel connected to your body and you push your limits.

Your iPod or the radio plays all the right songs, like a soundtrack following you through the day.

Productivity in work has to be a part of it. Reading something theoretically rich and challenging, and then producing something equally formidable. Something worthy of your time, worthy of a second look, of revising and improving and committing time to. Most importantly, something that makes the world a little better, even if it's just a tiny bit. Even just for today.

The perfect cup of coffee. Smooth, simple finish. Single origin. Already the right temperature when you get it, so that you don't have to wait for it to cool first.

The company of good friends. Physical interaction (hugs, etc). Being made to laugh.

Sunshine. Maybe drinking that coffee, while writing that work, while even listening to that iPod, while sitting in the sun. Those moments are the richest.