I'm 25 years old with AF, have been living with it for almost 3 years now and all that time I've been trying to exercise more and get healthier. I'm no way near over weight (and never have been) and I try to eat a balanced diet, but whenever I go out on my bike and have to cycle up a small hill or walk uphill while taking out in the countryside(Derbyshire mainly) my pulse often races and I feel a bit funny... no matter how often I exercise, the same thing happens. I'm wondering if this is somthing to worry about and if I should see my cardiologist regarding it? I'm on a beta blocker for arrhythmia (Bisorpolol), could this be causing problems with excersise? Or am I just worrying too much? I've noticed that I worry a lot more about things since having AF!