I can remember last year reading a post by Matt Mullenweg, lead developer of WordPress, about the way he works. In it he mentioned how he gets ‘into the zone’ whilst coding by listening to the same song over and over and over again:
Music is my muse and I listen to it all day. There’s a lot of jazz — Dexter Gordon and Sonny Rollins — but I’m also a big fan of Jay-Z, Beyoncé, and Method Man… When you’re coding you really have to be in the zone so I’ll listen to a single song over and over on repeat, hundreds of times. It helps me focus.
(my emphasis)
Music can have a massive effect on your productivity and it’s really important to find music that puts you in the zone that Matt talks about. I can only speak of what works for me, and what is currently my ‘productive song’, but I don’t think you’ll got too far wrong if you follow the suggestions below! 
1. Long
The track needs to be fairly long. Not your 3 minute pop song. You’ll get sick of that very quickly.
2. Repetitive
It needs to have a steady beat that’s not too fast and not too slow. I can’t tell you how fast that is (I think it probably varies between people). It’s probably about 100-120bpm for most of us, though.
3. Minimal lyrics
If you’re doing anything that involves writing words then you want as few lyrics as possible. Some lyrics are OK so long as it’s easy not to focus on them. 
In addition, I’d suggest that even if one of your favourite songs of all time meets the above criteria that you don’t use it as your ‘productive song’. Why? The association it will carry will displace the original reason you liked it…
You may find that you wear out your productive song after a while and my need to find another one. What’s my ‘productive song’ at the moment? Slightly randomly it’s a track by Apparat called Arcadia (Telefon Tel Aviv Remix) <–Spotify link. Don’t ask how I came across it – serendipity! 
Image CC BY skippyjon
