is this just a thought

it seems that for me anyway life would resume as normal if it wasnt for the 'thought' that i might panic or the 'thought' that i might have an anxiety attack....
physically i feel fine,mentally apart from those 2 constant 'thoughts' i feel fine....how can i get rid of these obsessive thoughts that seem to dog me so much....
i now work two days a week as a kitchen hand and it involves me cycling for around two miles and after work i forsce myself to go into town but the thought that i might panic is always there...very strange but it needs to be beaten