Jamie Cullum

For your afternoon jog, create a playlist on your iPod (or other mp3 player) of, say, Jamie Cullum's "I Could Have Danced All Night," "La Vie Boheme" from Rent, Chopin's Etude #5 ("Revolution"), and U2's "Elevation." Human nature demands you incorporate dance steps into your jog.

Sure, you may incur odd looks from parents walking their children home from school (the children will understand, of course), but your heart-rate will double, you'll extend your run for the fun of it, and you'll actually look forward to your next jog.