I did my cardio at night for a long, long time. I'm not much of a morning person. Never liked getting up early. But I finally worked my way into it, and now I like it. The way I motivated myself to move my cardio to the mornings was that if you can get up and get it out of the way, then you don't have it hanging over your head all day that you STILL have cardio to do after everything else is done. Also, I get up and do it when the kids are sleeping, so I don't have any interruptions anymore, and I bought a stair climber (a real one) so I could do it at home and not have to schedule around the gym just for my cardio. I either watch dance videos, which makes the time fly by the fastest, because the music and the beat help you keep up the pace, or sometimes I will rent a movie and watch it over several cardio sessions.
I used to feel queasy doing it on an empty stomach, but now I drink water every few minutes as I'm going along, and that seems to really help. For me the queasiness was because I take my vitamins and ECA just before I start my cardio, then do the cardio, then spend 15-20 minutes stretching, then eat my first meal. The ECA made me queasy on an empty stomach. Increasing the water I was drinking took care of the problem.
Hope this helps!
Fennec