Music does wonders for my work out sessions. It motivates me and really helps the time fly by. Unfortunately when it comes to the kind you need for sports, not all headphones are created equal. Even your nice white iPod earbuds will not cut it. In fact, you are almost always better off with specifically designed sport headphones.
The reason for this is simple. Whether you enjoy exercising at home, running outdoors, or hitting the gym, you will inevitably sweat. That's the common factor between each and every single sport. Electronics and sweat do not go too well together, so it's important to invest in a pair of waterproof headphones (or at least moisture resistant ones). Ideally, you should be able to wash your headphones after each session.
Sweat is the main culprit that kills regular headphones. But it's not the only aspect to consider when purchasing active headphones. As you work out, your body moves vigorously, putting your headphones and their cord through a lot of stress and jarring movements. This means flexible and durable material is a must. All that movement also implies that you will almost certainly get frustrated with normal earbuds, as they'll come out of your ears on a regular basis.
Your second requirement is therefore to find headphones that can be attached to your ears in some way. The popular over the ear neckband headphones are the first choice when looking for sport headphones.
You want to look for lightweight headphones that do not offer noise cancelling features. This is for your safety because you need to be aware of your environment when exercising outdoors (not being able to hear when you're outside is just asking for an accident!). If you exercise inside your house or indoors at the gym, then you can still consider noise cancelling headphones, as they'll certainly help to reduce the amount of (sometimes distracting) sound coming in from your surroundings.
Sports headphones are not really expensive, so try to shop for a name brand you can trust, rather than opting for cheaper no-name alternatives. The difference in build quality and sound will be noticeable in almost every case. The leaders in this field are Sennheiser and Adidas.
Finally, if exercising outside, please consider buying a model of headphones that includes reflective colors, as they will really help to maximize your visibility and enable you to exercise outside at night or in poorly lit conditions. Usually, the vivid colors employed by sport headphones manufacturer are pretty fashionable anyway, so you can certainly use them indoors as well.
The points above are a few important requirements when it comes to picking the best sport headphones that will both sound great and serve you well for a long time.