You'll live. First is what is your definition of "cardio"? (Steady state or HIIT stuff?) Regular steady state cardio fat burning is pretty much over once you stop it....higher intensity stuff involves more elevated post workout burn....but drink some water, take some Vit C, and if you want to pop some aminos feel free. Technically you are in an aerobic state even at work....so you could burn fat still, although probably not alot to get that excited about.
When in doubt....try it out...see what happens....add some coffee pre workout AM....enjoy.