Is floss habit hard to maintain ?

Not once you start experiencing the benefits. Here’s a tip: don’t just floss but after you floss use a little mouthwash like Listerine. Started this a few years ago and realized I stopped getting the usual winter cold I used to get every year. Then when you realize how flossing in combo with Listerine kills the stuff growing your mouth that causes colds, you’ll floss just to keep from losing the time that a cold costs you each year.

Yes, it requires a lot of effort to pass the boredom of doing it properly and you don't see a immediate benefit out of it.

It can be. I think the best way to maintain the habit is to find the time to floss that worst best for you. Rather than commit to flossing before bed wcah night, and skip nights because you're just too tired or fall asleep on the couch, etc, better to find a time in the day when energy is higher. I floss either in the morning or afternoon. Sometimes at night. If I know I'm going to have a late night, I'll floss during the day so that I make sure to get it in.