How to be reminded before leaving a place?

Hello:
My work is in the same place as my Home, only a different floor, so i need to find a trick to be reminded to do somethings before leaving my work place,
My timings are not fixed, so i can not set reminders at 12 A.M. FOr instance, but need to find a another trick or something to say to siri to remind me to do somethings before leaving my place
ANy help will be highly appreciated