I was also very passive and now I think I am very aggressive and I am trying to find a middle ground.
My tip that I give you is to pass from passive to active and check how other villains play while you are not playing, especially if the hand goes to showdown.
Then you will see players bluffing or, if they are not, you will see how they raised their chip pre-flop, on the flop, on the turn and on the river. In case you notice that they raise very high without having anything in hand or having a pattern write this down. This will give you courage so that when you get a hand in any of these you know what to do before you play, because every time you improvise the chances of going wrong increase.
It is also important to play a lot, but a lot, in tournaments that you can play without worrying about losing, because a lot of our passivity comes in the sense of human survival of not dying early, but in poker only the strong or crazy (depending on case) survive.