dont use too much spray or its REAL suspicious and will people will (maybe subconciously) sniff better to find out what smell is being covered up..

if youre in tshirt and shorts (im assuming cos thats what everyone runs in)
then its going to be difficult, so my advice is buy something from a dairy (uh... drug store) and then put it in that bag with say, a coke and a bag of chips or lollies..

but act normal and they wont know.

a ziplock wrapped in foil knocks out most smell, keep it in a container in the bottom of a cupboard or something, get fresh air into youre room often (my windows normally always open a crack)

and open it as unfrequently as possible..

or just keep a personal use bag in youre room and stash the half-O outside somwhere if you can.