Actually rode my bike to a doctor's appointment today, rather than taking the car, despite some light drizzle on the way out. 6-7 mile round trip (when you add on some errands to the end). It only takes an extra 5-minutes each way to go by bike vs. car (though it's faster by bike at rush hour), and I really liked getting some exercise. (And very glad that my bike didn't get stolen, despite having forgotten my lock. That's a big advantage of having a $65 Craig's List special rather than a fancy bike.)
The thing I love about riding is how alert I am when I get someplace. My mind is always super sharp after dodging cars in Boston traffic.