I like to exercise in the mornings to get it out of the way; otherwise, the later in the day, the more excuses I have. This is good for when I am tired (and I am really really tired) after work. Also since I start class again on Monday, I'll have a packed schedule so working out in the mornings is best
Hopefully when I get fitter I will be more addicted to exercise and will be able to look forward to it... right now it's at the stage where I am like "ugh do I have to get up... really" :P