"Why aren't you signed up for the 401K?"
"I'd never be able to run that far."
--Scott Adams; Dilbert (4/2/01)
Fartlek (n.)--Swedish for "speed play", a type of loosely structured interval training for runners, cyclists, and in-line skaters. It combines anaerobic segments with aerobic ones. Said to build strength and speed. (also relieves boredom)
Feeling energetic when Black Eyed Peas' "Let's Get It Started" started playing, she decided to pick up the pace and do a 1/4 mile fartlek.