Exercise instructors know the key to starting any good workout: Press play.

“If you play motivating music, people work harder,” says Julz Arney, education programs director for Schwinn Cycling, who talked up the importance of tunes at a Virginia fitness convention earlier this month.

Slapping together your favorite hits can help you complete one more set or lap. But if you really want to make the most of your music when you’re exercising solo, it pays to borrow techniques from the pros.

For starters, forget about shuffle. You want a playlist that begins with slower selections, builds up intensity and then returns to a more relaxed beat for the cooldown.

It’s also helpful to “map out” each song, Arney says. Take note of a tune’s distinct sections and choreograph your workout accordingly. A chorus, for instance, can be a perfect cue that it’s time for a sprint.

Arney uses a range of musical styles to keep students’ attention and to break up workouts into manageable chunks. “You can do 10 minutes of house, 10 minutes of blues and 10 minutes of hip-hop,” she says. “It makes the time fly by.”

You can even try throwing in classical music for a change of pace. Tish Niffenegger, group exercise director for Fitness First clubs, is partial to “The William Tell Overture.”

Figuring out what to play doesn’t require becoming a full-fledged DJ, Arney says. But she seeks inspiration from Spotify, which lets users create, share and subscribe to playlists so they can easily get music suggestions from friends.

Make sure some of those pals are exercise instructors and you’ll be able to re-create your favorite workouts anywhere. Maybe you really enjoyed a cycling class? Borrow the songs and the structure, and you can do the same routine on the elliptical or treadmill, Arney says.

Don’t hesitate to ask your instructor for the title of a song you like, says Mike Gray, group exercise manager at Equinox Tysons Corner. He’s flattered to get questions from his students about his tunes, although he has to explain that the music on his CDs isn’t exactly what you hear on the radio.

Like most instructors, he relies on fitness music companies that rerecord hits specifically for the gym (see below). It used to be difficult to get your hands on this music if you weren’t in the industry, but that’s changed as the Internet has directed consumers to companies such as Power Music, Baltimore-based Dynamix and the District’s Yes! Fitness Music.

Now, anyone can just scroll to the “fitness and workout” section of iTunes. “The bigger market is the fitness enthusiast in their living room, doing their thing,” says Mike Babbitt, co-owner of Yes!

Several fitness music companies have launched services that let customers build personal mixes online — you select the songs, choose the beats per minute, and decide whether you want the songs in a continuous mix or separated by breaks.

Keep in mind, at some point in any good workout, you’ll need to stop for water.

Music Factories

The fitness music industry solves two issues: Gyms don’t want to pay to play original artists, and many popular tunes have slow sections. “You can’t work out to an Adele song because it has no beat, so we engineer it for energy,” says Power Music’s Mitch Rolfe. This can lead to cheesy covers, but in the age of Auto-Tune, it’s easy to make a convincing Rihanna substitute.

Can’t Be Beat: Two Tempo Apps

Tempo Magic Pro ($5) lets fitness enthusiasts adjust the beats per minute of any song on their playlist without distorting the vocals (no chipmunk singers!).

Tempo Power ($5) has similar functionality, including the option of gapless playback. But it can slow down or speed up songs more (35 percent vs. 24 percent).