How come?

This is my observation today. For some reason my nose was running.(funny expression isn't it) profusely. Used tissues were piling up around me. Wanting to get my half hour on the tread mill behind me (regardless of my physical ailment) I armed myself with a wad of Kleenex stuffed up my sleeve and started my pacing. Would you believe my nose never "ran" again today. What 's the name of that chemical that's secreted during exercise??