A habit is, by one definition, “an acquired behaviour pattern regularly followed until it has become almost involuntary”. While acquiring habits takes effort and is quite hard, losing them is easy and can happen surprisingly quickly.
Some habits are often built because of the people around you. And if in the wrong company, previously held good habits can get lost.
This happened to me recently. And although I had a faint realisation while I was losing this habit, it only fully hit me when I had lost it. To prevent this happening again, I have to remind myself to not just actively seek the good from people around me but also shun the bad.
Double the effort, double the reward.