Waking for suhoor and keeping it after Ramadan
Every Ramadan proves the same thing: you can wake before dawn for a month when there's a reason and everyone around you is doing it too. The month ends; the proof doesn't.
Keep the anchor, drop the meal
Suhoor gave the wake-up a job. After Ramadan, Fajr itself is the job — same time, same quiet house, same reward multiplied. Keep the bedtime you kept in Ramadan for two more weeks and the habit survives the transition.
Keep the people
The other Ramadan ingredient was company — family up together, group iftars, full masjids. Recreate it in miniature: a handful of friends who check in at dawn and notice when you don't.