I set my clock forward by random amounts, changing it every few weeks.
My problem is that getting up in the morning is one of the most difficult things I have to do. By setting the clock at varying differences from real time, I force myself to wake up enough to remember what the difference is, which is how I figure out whether I've got time to sleep a little later. If I set the clock to real time, I wake up and think it's probably not what time it really is and then I'm late.
I also set my alarm a good amount ahead of when I should start getting up. This gives me that "I don't REALLY have to get up so I can hit the snooze bar" feeling.
So, if I have to get up no later than 7AM, I set the alarm to 6:45, which is actually 6:30 because I've set the time ahead. So when I hit the snooze bar a few times, I end up getting up at what is actually several minutes before 7AM, which means I'm reasonably on time for work and maybe even have time to eat breakfast.
The reason I randomly change the amount of difference between real time and clock time is twofold: one reason is that I start to remember what the difference is when I wake up, and therefore don't have to wake up as much to figure it out and start to sleep too late again; the other reason is that when I'm fighting to turn off the alarm at 6AM, I usually start hitting buttons randomly and sometimes I change the time on it, and then I leave it there because it gives me that extra challenge.
Honestly, getting me awake in the morning is extremely difficult, even when I'm trying to wake up for something I've been DYING to go do and which I planned myself, let alone for something like work or an event I don't want to be at. My subconscious sets up elaborate waking dreams for me which make me think that the alarm which is buzzing is actually something else, something involved in whatever I'm dreaming about, which I need to turn off. So I do, and then continue dreaming until it goes off a few more times and the buzzing breaks through the dreaming to my conscious mind, at which point I start cursing my subconscious for being so efficient. Sometimes I've woken up thinking "What the hell was I dreaming about?" I can't even remember now any of the things my brain has come up with to cover the fact of the alarm going off.