How to choose the best running headphones for you

A decent pair of sports headphones are a very worthy investment. Research has shown that the right type and tempo of tune can keep you in the zone for longer, and we've all ran up park steps to a suitably bombastic soundtrack like we're Rocky. Even if we've then keeled over at the top.
So, lace up your running shoes, strap a smartphone to your arm and prepare for musical motivation.
The key here is a secure but comfortable fit, with sound performance good enough to keep you motivated and happy when you're pushing yourself to the limits.
After years of using headphones during runs, gym visits and rugged, outdoor pursuits of all kinds, we'd say fit is more important than being rugged. In fact, a pair of standard, non-sport earphones can work perfectly well if they anchor in your ears well.
Presumably some people sweat more profusely than us - Christiano Ronaldo, for one - or live in places where it rains torrentially at all times, or are particularly rough with their headphones. If that's you, go for one of the chunkier models here.
The other main thing to consider here is whether you want traditional wired or Bluetooth wireless 'phones.
The former offer an unshakeable audio connection with no battery life issues, but the latter gives more freedom, and less risk of yanking out/breaking the cable (because there isn't one) albeit at the expense of having one more thing to charge and occasional audio drop-outs. These are inevitable if you keep your music player in a hip pocket but tend to be less frequent if you have them higher up your body.
Most of these are Bluetooth, though, cos that's the way the market's going.
They're also suitable, to a greater or lesser extent, for cycling (be aware of the safety implications here though, please guys), pumping iron, cross training, and anything else you can do whilst listening to music and sweating profusely.