I think that having something to look forward to during the day might not work for some of us because we're more concerned with how we're feeling at the specific moment than having something enjoyable later in the day. At least that's why it wouldn't work for me.

If imagination doesn't work, you could set up some type of negative reinforcement that will only go away if you get out of bed?

I know that they have alarm clocks that are designed to be a pain in the *** to turn off, like the ones that run around your room or the ones that fly. The idea is, you'll want to turn off the alarm because it's annoying. And after you chase it down, you'll be fully awake and less likely to have to go back to bed.
And always set it to snooze, not off. Maybe the threat of it going off again is enough to make you get up.

Or
Make some type of commitment for an appointment in the morning that you have to check into in the morning. And there will be a punishment of some type if you don't make this appointment.

The first few days are the hardest because you need to build the habit