The double-fudge-loaded cheesecake derails your healthy eating habits.
Disturbed sleep derails your writing habit.
Surprises in your schedule derail family time.
Unexpected behavior from others derails your best intentions to be the best possible version of yourself.
Time goes into stealth mode and derails your blogging routine.
Some of those seem trivial. Others are major events. Each of us would rate each of them a little differently.