Proud Mary really, but just Mary for short.
Mary is the only song I have found that actually makes me get running on the treadmill.
Me and running are never going to be friends but Me and Mary, we can belt out a kilometre on the treadmill at a fast pace.
I know I have a few friends and twitter peeps trying to improve their running skills, so here you go, just add Mary to the Ipod, the smart phone or even the CD player.
If you're lucky enough to not be running, put Mary on while you cook tea and you will notice how much more fun it is, be careful of high leg kicks and disco duck moves, don't go putting your back out.
If you need more hard factual evidence - just check out Tina's legs after a few decades of prancing around to Proud Mary. The lady has legs that I want when I am 60+.
Not so secret weapon any more.