This was by far Olivia Newton-John's biggest US hit. Heck, Billboard ranked it the 6th biggest hit of ALL TIME. All for a trendy song and video made possible by the early 80's aerobics craze. A great song, to be sure. A song full of double entendre and, well, suggestive lyrics and an accompanying video (let's just say ONJ wasn't talking about the latest Jane Fonda video when she was talking about a "suggestive movie"). A cultural phenomenon, which is still fondly remembered today.
It was such a cultural phenomenon, it was featured thirty years later on an episode of Glee, where Olivia did a duet of the song with Jane Lynch, somewhat parodying the video, and EVERYONE GOT THE REFERENCE.
Of course Juliana Hatfield covered this song, too. Go over to Totally Covered and check that out!