R is for Recharge.
One of the problems of keeping everything you have to do in your system is that there's always something more that you could do. Being more productive is one thing, but working yourself into an early grave is something entirely different. It's important to find time, however many things are left on your to-do list, to take a break from work and recharge your batteries.
Please note, though, that this entry is recharge, not relax. Finding a way to relax is a great way to recharge, but if you'd rather blow the cobwebs away charging down a twisty singletrack on your mountain bike, or get the adrenalin pumping cheering on your football team, then that's fine. Just get away from the daily grind.
I must admit, from time to time I do add fun things that I want to do to my to-do list. After all, it is my list of things that I've decided to do. It usually just exhibitions or talks that I want to attend, but sometimes it's just as simple as "go our for a bike ride". That's more of a last resort; if I feel that I'm getting sucked into too much work and need that little extra push to get away from the computer.
And to show that I practice what I preach, when this entry is posted (the wonders of computers, being able to work whilst I'm not there) I'll be up in the Alps, getting a last day of snowboarding in before the end of the season.