At a time I woke up 6:30 to get to work 7:00. Now I get up 5:45 to go at work 6:30.
The tow factors that have made me do that, is force and want. I was "forced" to wake up earlier because it was longer distance to the work place. I had to be there at 7, but chose 6:30 because I gained a want.
After setting the alarm on my phone 5-10 min earlier regularly, it wasn't that hard to wake up, and it didn't feel like I lost a lot of sleep.