You would imagine that singing favorite songs anywhere private would not be such a big thing, especially if you know all the lyrics by heart. If, like myself, your brain resembles a sieve and information stored there escapes through the tiny holes, you might need a bit of prompting to help you remember the lyrics. And there is no easier way than resorting to karaoke.
To get away from your comfort zone though, you would need to try something which is not completely new to you but which you are not entirely familiar with. The accompanying music is already of great help so it is singing in sync and in tune that is relevant for you, if you want to see any positive changes in your singing. Vocal training cannot be ignored if you really want to progress to a certain level so some form of commitment is necessary.>