LOL! Over lunch is good if that fits your schedule--I used to do that on my lunch hour at work to help me offset stress-induced fatigue. These days I work from home and I prefer to exercise before breakfast, so that way it's out of the way before I try digesting anything. However I should mention that what I do before breakfast isn't my cardiovascular routine; it's more like a standing version of Yoga--sort of--it's actually called Chi Kung and basically involves standing in a deep stance (thus relaxing the upper body) and doing deep breathing while rotating through a series of five hand postures that stretch different parts of the lungs/internal organs. I do that for about 30-45 minutes every morning, followed by some stretching, after my shower and before eating, which helps wake me up for the day. Stuff that involves heavy cardiovascular activity I prefer to do later in the day, mostly because the Chi Kung is supposed to be relaxing so I don't like to do something high-intensity right afterwords and therefore I try to space my workouts out. But if I was doing cardio/weightlifting as the main focus of my routine I'd probably do that in the morning. I'd probably work out over lunch if I was eating lunch at work--I used to do some light Chi Kung stretches over lunch and my 15-minute breaks to help keep me awake at work. Do you have a gym at work?--that's nice to have.