Running while TTC

So this seems silly for me to even ask but TTC has put a lot of stress on my marriage and my depression (which I have suffered from for as long as I can remember). I recently started running to boost my spirits but a doctor at work (I am a nurse) told me I should not start running if I am trying to conceive. this seems a little silly to me and the Doctor who told me this is a cardiac doctor so I am wondering if this is true or not? Has anyone heard anything related to running and TTC?