What Habits Takes the Longest to Become Consistent?

The hardest habits to make consistent are usually the boring ones, like sleeping on time, exercising, eating better, saving money, or studying every day.

I think habits take longer when there is no quick reward. Nobody gets excited about saving $5 or going to bed early. The trick is to make them so easy that you can still do them on a bad day. Consistency usually comes from repeating a small action, not trying to be perfect.