Although music can help you relax, it can do so much more. Experiment to find what works best, but here's a sample of what I like:

"Symphony No. 9 in D Minor," Beethoven
"Thunder Road," Bruce Springsteen
"Still Young," The Cat Empire
"Three Little Words," Branford Marsalis
"Free It Up," Destra (feat. Sean Paul)
"Waiting on the Stage," Machel Montano (feat. Badjohn Republic)
"Like a Surgeon," Weird Al Yankovic
"Keeping Your Head Up," Birdy 
"Glow," Nelly Furtado [opening words before the song]
"Emergence," R. Carlos Nakai
"Thunderstruck," AC/DC 
"Clarinet Quintet in A Major, K. 581," Mozart
"Party All The Time," The Black Eyed Peas