Try and set couple of sessions a week for some light cardio.. but also try to do bits and peaces through the day just for couple of minutes at the time.. just enough to make your heart beat a bit faster, and then carry on with your day as usual.
For example if you need to go up the stairs try going fastest you can, or skipping the stairs, just long enough to bring your heart beat up, and then carry on as normal.. Or do 30 sec of jumping jacks when you wake up.. little bits like that trough the day will also make a difference..
You will start noticing improvement very quickly if you do it every day few times..
Let me know how it goes :)