Trying to start or stop a habit without any accountability is a disaster waiting to happen. It's easy for the evil inside to convince you to have another smoke or sleep in late again.
But if you have someone else holding you accountable, you can leverage the power of peer pressure to stay on track.
Ask someone else in your house who wakes up early to make sure you're awake - it can be a sibling, parent, spouse, etc.
Or you can have one of your friends call you in the morning to make sure you're up.
Along with an accountability partner, you need to hold yourself accountable by tracking your progress. Every morning that you wake up on time, use a habit tracker (this can be a calendar) to keep a record of your progress.
It helps to visualize how much progress you're actually making, and your accountability partner can look at it too.
Slow & Steady
Trying to go from a 10 AM wake-up routine to a 6 AM wake-up routine in one night is a disaster waiting to happen. Making it easy is a big part of the 5 steps of behavior change, so keep that in mind when adjusting your sleep schedule.
When I was changing my sleep schedule, I tried waking up at 6 off the bat and it failed miserably.
After that, I set my alarm 10 minutes earlier every night and it got to the point where I was waking up at 6 AM and falling asleep at 10 PM every night, without noticing much of a change.
You can apply the same strategy by setting your alarm 5, 10, 15, or 20 minutes earlier each night until you've reached your wake-up time goal.
Make a Commitment
Waking up early for yourself is harder than waking up early for someone else because when you have a prior commitment that requires you to rise early, the fear of being late makes it much easier to wake up.
For example, when I schedule time in the morning for sales prospecting (something I do without anyone else) it's much harder for me to get out of bed. In the past, I'd schedule 3 hours for prospecting but I'd only end up prospecting for an hour because I decided to sleep in late.
Conversely, when I book sales meetings in the morning, I'm forced to wake up early to attend the meeting - if I sleep in, I won't make the sale and my company will look bad.
You can make commitments in the morning when you're getting used to waking up early, and then remove them from your schedule and replace it with things you actually want to do in the morning, like journaling, exercise, etc.