I've long been an avid runner, but I have to admit that until a handful of companies started offering running tours in the U.S. and abroad, I never really thought of taking an organized tour that required me to put on my training flats. The trend seems to be catching on, considering a company called City Running Tours has recently expanded into Washington, D.C. and Chicago after successfully introducing the concept in New York City one year ago. As of September 1, they'll be in San Diego, too.

Led by experienced runners with insider knowledge (and rock hard calves), the tours take you past scenic points of each city and range from one mile to more than 20. Don't like any of their planned routes? Just ask and City Running Tours will customize a run to meet your needs--because any opportunity to get some exercise on vacation is probably a good one.

Contact City Running Tours, 877/415-0058, cityrunningtours.com; guided runs up to six miles are $60, each mile afterwards is $6.

Related: Check out our recent piece Running in Places for tips from experts and downloadable running maps for 12 cities!