Do what works for you. Don't set yourself up for failure. Put yourself in a position that will give you the results you want. For example, I like to run and exercise in a general way. I do not like being smothered, even at 6am, by humid air. So if I plan to run and then don't get ready until 8am (hah 10am) I'm not likely to actually get much good out of any workout that I do, if I do even end up running. So we got a gym pass last week and I'm currently loving air conditioning, treadmills and knowing how far and hard I'm really running.
Another example: I sometimes have a really hard time waking up in the mornings. I have my routine down to the nanosecond so that I can just get up and race, tornado-like, around my house and get out the door just in the "Nick" of time. Lately I've wanted to photograph the early morning light, but when the alarm clock chirped I usually hit snooze because the cost outweighed the benefits. And yet those pictures are of the sunrise, not sunset. I've been awake for three sunrises in the last two weeks by being awake on the "wrong" side of morning rather than getting up early. Do what works for you.