jkay,
You answered your own question with the answer I was going to give, for the reason I was going to give it!
Of course, there is some personal variation on this--for some people, working out later in the day works better for them and they're able to maintain it consistently.
But what you said sounds pretty much like me. Other times in the past that I've tried to get in the habit of working out, I did it in the afternoons after work because I didn't want to get up earlier in the morning. And I never was able to make a habit out of it because I'd get to a point where I'd start saying "I had a long day, I'm too tired to work out..."
When I started BFL I decided I'm going to get up at 6am every morning for my workout no matter what... and I'm going to make "be in bed by 10pm" a rule to make sure I'm able to get up on time. And it's been working--getting up early took some willpower at first, but now that I've gotten in the habit it is almost effortless, especially compared to getting up the motivation to exercise after a long and tiring day. And it's a wonderful feeling going through my day knowing I've already finished my workout... at 7:30am I'm eating meal 1, I already know what I'm eating the rest of the day (and if it's a day I don't have time to cook, the meals are already prepared), and my workout is done--I
start my day feeling like my day is already a success! I don't think I can articulate just how much that contributes to my ability to stick with the program.
So, if I were in your position at this point I would be heavily leaning toward getting up a little earlier to stick with morning workouts.
