For me, the key to productive, contented living is decluttering.
Life seems to default to an excess of possessions, activities and pursuits. It takes intention and effort to organize a distracted state of living into one that is simple and peaceful. Decluttering involves making do with the minimum required to achieve your goals, and systematically winnowing out what isn't earning its keep.
I apply decluttering to every aspect of my life. Working at two clinics had introduced unnecessary complexity to my week, so this summer I resigned at the HIV clinic to exclusively practice refugee medicine. I focus on three hobbies: gardening in summer, knitting in winter and photography year-round. No one looks inside my closet without remarking that it's the most pared down collection of clothes they've ever seen. My kids have a modest selection of thoughtfully chosen, well-loved toys. I thin my patients' charts ruthlessly. My blog has the cleanest layout possible and I haven't added any extra applications to my Facebook page.
Learning to say no is a major part in decluttering the calendar. (I was 30 when I finally learned to do this well.) When I do make commitments, I make them for a defined period of time. I'll join a knitting group for one winter, for example, or keep a blog for one year. When I take on a new position at work, I quietly decide up front for how long I'm willing to commit. At the end of the given time, I reassess. That way every obligation has an expiry date and can be renewed or replaced.
To use my time most efficiently, every weekend I plan the week ahead, including penciling in activities for my downtime. My kids are all in bed by 7:00, and that's three full evening hours for me - if I can escape the call of the Internet, probably the most distracting, time-wasting, mind-cluttering force out there. Some useful tools to make Internet use efficient are feed readers, which eliminate the need to visit blogs to check if they've been updated, and Firefox's pageaddict, which monitors the time you spend at different sites and allows you to set restrictions on your visits to inane, yet compelling sites.
Decluttering is a way of life. This method agrees completely with my personality, and I purge, streamline and consolidate with pleasure. Cutting out the extraneous allows for the clutter I do enjoy: a house overflowing with kids and a slate full of patients.