More aggressive

So I decided to talk to my boyfriend about what he likes and dislikes about us having sex, just trying to see what I could do better and such, now normally I'm the bottom, but my boyfriend has somehow turned me into a top for him, but I'm not aggressive at all, (something from when I was a bottom only player), but I found out he would like me to be aggressive, more dominate, any advice on how to do this? It's so far from who I am I have no idea how to be more aggressive.