habit

我总是出于习惯购买同一个品牌。

I always buy the same brand out of ___habit.

我总是出于习惯买同样的牙膏。

I always buy the same toothpaste out of ___habit.

他无法改掉在咖啡里放糖的习惯。

He can't break the ___habit of putting sugar in his coffee.