Flood your brain with good influences.
It is hard to swim against the tide, so make sure the tide is going in the right direction.
Read, watch, and listen to things that encourage your new habit.
You are the average of the 5 people you spend the most time with. Make sure you want to be like them.
Whatever you are reading and watching is what you start believing about the world. Make sure it's what you really want to believe.