Finding good headphones for working out can be difficult. All of us have different needs when it comes to workout headphones. I am going separate the best headphones for working out so that they match up with your workout preferences.

If you prefer to go for a run and listen to music at the same time your best headphones for working out are going to be the over the ear clip style headphones. The headphones for runners pictured here allow you to control the volume conveniently on the cord. I've tried going for a run with earbuds and traditional headphones and there is too much movement going on. The over the ear style is the way to go.
For the gym rat that spends a lot of time using free weights; the best headphones for working out are going to be the wrap around style. I'm referring to the neckband style headphones for the gym I have shown here. Heavy lifters prefer to listen to powerful base for the most part (I know there are some easy listening power lifters out there). The neckband style provides volume directly into the ear and the cords will stay out of your way.
Now there are also people that enjoy working out and socializing at the same time. If you live a busy lifestyle, or you just can't stay away from your cell phone during your workout. The best headphones for working out for you may be the bluetooth wireless style. They will cost quite a bit more, but their are obviously advantages to being able to workout with no wires. These headphones for working out are also sweatproof, making them ideal for the gym. It is nice to be able to receive calls while you workout.
There is no substitute for headphones that get you motivated to work out. If you are having trouble getting in the mood to workout, find some great fitness headphones, it will make working out fun again.