Good one, Lucy Dan!
I have a very quirky superpower, which is that if I set an alarm, my brain will always wake me up a few minutes before it goes off.
Probably because I really hate being woken up by an alarm clock, so my brain is cutting me a break.
But this doesn't work if I don't set the alarm.
I can't just tell myself to wake up at 7:30 and then wake up at 7:30.
It only works if I set an alarm to wake me at 7:30.
Then I'll wake up a minute or so before 7:30 so that I've got time to shut it off.
Of course, now that I'm retired I can pretty much get up whenever I want to.