Well, you can tell by the way I use my walk

Various guidelines call for 30 minutes of "moderate intensity" exercise five days a week but people have a hard time knowing what "moderate intensity" means. According to MedPage Today:

If you channel the Bee Gees' long-ago hit, "Stayin' Alive," as you walk, it can help you get the pace right.The old disco favorite has a beat almost perfectly matched to the minimum, 100-steps per minute it takes for a half hour of proper cardio exercise. That's 3,000 total steps, according to Simon J. Marshall, Ph.D., of San Diego State University, and colleagues.His group's experimental findings were designed to provide a rough guide for men and women who use a pedometer to monitor their activity. The recommendations were reported in the in the May issue of the American Journal of Preventive Medicine.

As a side benefit, if you see someone having a heart attack while you're walking along at a "moderate" pace, the exact same song has been recommended  as the right pace for performing chest compressions in CPR. I remember this story a few months back from MSNBC

Under most circumstances, it's best to keep the beat of the Bee Gees song “Stayin' Alive” out of your head, but heart specialists have come up with one good reason to remember: It could save someone's life.Turns out the 1977 disco hit has 103 beats per minute, a perfect number to maintain — and retain — the best rhythm for performing cardiopulmonary resuscitation, or CPR.A small study by University of Illinois College of Medicine researchers in Peoria has found that 10 doctors and five medical students who listened to the "Saturday Night Fever" tune while practicing CPR not only performed perfectly, they remembered the technique five weeks later.